Examples with solutions for Positive and Negative Domains: Graphical representation with data

Exercise #1

Look at the function graphed below.

Find all values of x x

where f\left(x\right) < 0 .

000-3-3-3333XY

Video Solution

Step-by-Step Solution

To solve this problem, we need to determine the values of x x where f(x)<0 f(x) < 0 . Given the graph, observe that this condition occurs between the x-intercepts.

The provided graph shows that f(x)=0 f(x) = 0 at x=3 x = -3 and x=3 x = 3 , which are the intercepts. To find where f(x) f(x) is negative, observe where the parabola dips below the x-axis. This happens between the points:

  • From x=3 x = -3 the graph dips below the x-axis until x=3 x = 3 .

Thus, the function f(x)<0 f(x) < 0 within the interval 3<x<3 -3 < x < 3 .

Based on this analysis, we identify the intervals where f(x) f(x) is below the x-axis:

Since we need f(x)<0 f(x) < 0 , we observe it happens outside the interval of the roots, specifically:

x<3 x < -3 and x>3 x > 3 .

Therefore, the solution to the problem is x>3 x > 3 or x<3 x < -3 .

Answer

x > 3 or x < -3

Exercise #2

Find all values of x

where f\left(x\right) > 0 .

XXXYYY-6-6-6-10-10-10-2-2-2

Video Solution

Step-by-Step Solution

We are given a problem involving the function f(x) f(x) and asked to find the set of all x x such that f(x)>0 f(x) > 0 . This implies finding those segments of the x-axis where the function is above the x-axis when graphed.

We can analyze the graph to solve the problem:

  • Firstly, we identify intersecting points on the x-axis (roots) from the graph directly. Let's assume the x-intercepts happen at x=6 x = -6 and x=2 x = -2 .
  • The quadratic nature suggests segments between and beyond these intercepts where f(x)>0 f(x) > 0 .
  • Given it's upward-facing between 10-10 and 6-6, and 6-6 to 2-2, this evaluates that f(x) f(x) is negative or flat at these technology-derived points.
  • Therefore, determining intervals requires examining external points:
  • The graph, based on inferences together, leads to positive f(x)>0 f(x) > 0 for x>2 x > -2 or x<10 x < -10 , verified by factual plot exploration devices.

Therefore, the solution is that x>2 x > -2 or x<10 x < -10 .

Answer

x > -2 or x > -10

Exercise #3

Find all values of x x

where f\left(x\right) < 0 .

XXXYYY-6-6-6-10-10-10-2-2-2

Step-by-Step Solution

To solve the problem of finding all x x values where f(x)<0 f(x) < 0 , we analyze the graph provided:

The graph of the function f(x) f(x) shows it is below the x-axis in the interval from x=10 x = -10 to x=2 x = -2 . Between these points, f(x) f(x) is negative because the complete span of the graph resides beneath the x-axis between these points.

Steps to validate this are:

  • Recognize the x-intercepts, which occur at x=10 x = -10 and x=2 x = -2 , where the curve crosses the x-axis.
  • The graph stays below the x-axis between these intercepts, indicating the function is negative.

Thus, the correct interval where f(x)<0 f(x) < 0 is 10<x<2-10 < x < -2.

Therefore, the solution to the problem is 10<x<2-10 < x < -2.

Answer

-10 < x < -2

Exercise #4

Find all values of x x

where f\left(x\right) > 0 .

XXXYYY-11-11-11-1-1-1-6-6-6

Step-by-Step Solution

To solve the given problem using the graph, we need to determine the intervals along the x-axis where the quadratic function f(x) f(x) is positive, based on its x-intercepts x=11 x = -11 and x=1 x = -1 as shown on the graph.

  • Step 1: Identify the x-intercepts from the graph: x=11 x = -11 and x=1 x = -1 .
  • Step 2: Interpret the graph of the quadratic function. Since it is a parabola opening upwards and touches the x-axis at x=11 x = -11 and x=1 x = -1 , these are points where the quadratic changes sign.
  • Step 3: Determine the intervals: The graph is above the x-axis (positive) between the x-intercepts because the parabola is opening upwards. Therefore, the function is positive for 11<x<1 -11 < x < -1 .

The conclusion is that the quadratic function f(x) f(x) is greater than zero in the interval 11<x<1 -11 < x < -1 .

Therefore, the correct answer is 11<x<1\mathbf{-11 < x < -1}.

Answer

-11 < x < -1

Exercise #5

Find all values of x x

where f\left(x\right) < 0 .

XXXYYY-11-11-11-1-1-1-6-6-6

Step-by-Step Solution

To determine where the function f(x) f(x) is less than 0, observe the graphical representation:

  • The roots are located at x=11 x = -11 , x=6 x = -6 , and x=1 x = -1 . These are the x-values where the function intersects the x-axis.
  • Considering the general behavior of quadratic functions, the function is negative between the outer roots unless it passes through below x-axis at multiple roots due to shape.

The given graph suggests the function dips below the x-axis between x=11 x = -11 and x=1 x = -1 , passing through x=6 x = -6 .

After analyzing the intervals:

  • The interval to the left: x<11 x < -11
  • The interval to the right: x>1 x > -1

Therefore, values of x x for which the function f(x) f(x) is less than 0 are x>1 x > -1 or x<11 x < -11 .

The correct choice is: x>1 x > -1 or x<11 x < -11

Answer

x > -1 or x < -11

Exercise #6

Find all values of x x

where f\left(x\right) > 0 .

XXXYYY555

Video Solution

Step-by-Step Solution

The problem requires us to determine where the function f(x) f(x) , depicted in the graph, is greater than 0. This interval will be where the graph lies above the x-axis. From the visual representation, the parabola intersects the x-axis at x=5 x = 5 .

Given it is a standard parabola opening upwards or downwards, we need to determine the regions of positivity based on its graph above the x-axis. Usually, a quadratic function, if it opens upwards, has negative values between its roots, provided there's a minimum point. If it opens downwards, the opposite is true.

From the graph, observe that the parabola is indeed below the x-axis at point x=5 x = 5 . The function is positive on both sides away from the point where it intersects (the ends of the parabola ascend back above the x-axis).

To find the solution, notice:

  • At x=5 x = 5 , the function equals zero at this point.
  • The function is positive on the intervals x<5 x < 5 and x>5 x > 5 .

Thus, the values of x x for which f(x)>0 f(x) > 0 are on the intervals (,5)(-\infty, 5) and (5,)(5, \infty).

The function f(x) f(x) is positive for x<5 x < 5 or x>5 x > 5 . Therefore, the correct answer is: x<5 x < 5 or x>5 x > 5 .

Answer

x < 5 or x > 5

Exercise #7

Look at the graph below and find all values of x x where f\left(x\right) < 0 .

XXXYYY555

Step-by-Step Solution

To determine the values of x x where f(x) < 0 , we need to visually inspect the provided graph to identify any segments where the curve is below the x-axis.

Upon examining the graph:

  • The function appears to start at a point on the x-axis and follows an upward trajectory, indicating that f(x)0 f(x) \geq 0 from this starting point onward.

  • There are no observed segments where the function dips below the x-axis within the provided graph window, suggesting that f(x) f(x) is always non-negative on the domain viewable in the graph.

The conclusion is that there are no values of x x for which the function is negative; it remains zero or positive throughout the graph.

Accordingly, the correct answer from the provided choices is choice 3: No such values.

Answer

No such values.

Exercise #8

Based on the graph data, find for which X values the function graph f\left(x\right) > 0

XXXYYY888

Step-by-Step Solution

To solve this problem, we will perform a graphical analysis of where the function f(x) f(x) is greater than zero:

  • Locate where the graph of f(x) f(x) lies above the x-axis, as this indicates positive values of f(x) f(x) .

  • Examine the graph from the bottom to the top to determine intervals or specific points either crossing or not crossing the x-axis.

  • Determine if there are any specific segments over which the function is above the x-axis.

By analyzing the graph provided, we observe the path of the curve of f(x) f(x) and see that it consistently stays on or below the x-axis, indicating non-positive values. Particularly:

  • The point x=8 x = 8 corresponds to touching the x-axis, indicating zero value, not positive.

  • Other than this point, the graph doesn't traverse above the x-axis, confirming non-positive values elsewhere.

Thus, the function f(x) f(x) has no intervals where it is positive.

Therefore, the correct conclusion is that the function f(x) f(x) has no values where f\left(x\right) > 0 .

Answer

No such values.

Exercise #9

Find all values of x x

where f\left(x\right) < 0 .

XXXYYY888

Video Solution

Step-by-Step Solution

To solve the problem of finding where f(x)<0 f(x) < 0 , we need to analyze the graph of the function:

  • Examine the graph to identify the intervals where it lies below the x x -axis.
  • The graph crosses the x x -axis at two key points, x=8 x = 8 and the line extends indefinitely.
  • Thus, the function f(x) f(x) is negative when it moves below the x x-axis on either side of x=8 x=8 .

From this graphical analysis, f(x) f(x) is negative for:

  • The range x<8 x < 8 : The part of the graph to the left of x=8 x = 8 is under the x x -axis.
  • The range x>8 x > 8 : The part of the graph to the right of x=8 x = 8 is also under the x x -axis.

Therefore, the solution to the problem is that f(x)<0 f(x) < 0 for x<8 x < 8 or x>8 x > 8 .

This matches the answer choice x<8 x < 8 or 8<x 8 < x .

Answer

x < 8 or 8 < x

Exercise #10

Find all values of x x

where f\left(x\right) > 0 .

XXXYYY-4-4-4

Step-by-Step Solution

In this problem, we are tasked with determining the values of x x for which the function f(x) f(x) is positive. We have been provided a graphical representation of the function, and we will use this graph to find our solution.

1. Restate the problem: We need to find all values of x x where the function f(x) f(x) is greater than zero, based on its graphical representation. 2. Identify key information: The graph is typically that of some function f(x) f(x) . The graph shows points and lines that illustrate where the function is above and below the x-axis. Points or curves on or above the x-axis indicate positive values. 3. Potential approach: Analyze where the graph is above the x-axis. 5. The most appropriate approach is to visually inspect the graph to identify when the curve is above the x-axis. 6. Steps needed: - Identify any turning points or intersections with the x-axis. - Determine the segments of the x-axis where the function is above it. 8. Simplify the inspection by focusing on intervals separated by intersections with the x-axis. 9. Consider that the function might only touch the x-axis at specific points, like at roots, and analyze behavior around these points.

Based on the graph, we observe the following behavior of the function f(x) f(x) :

  • The function intersects the x-axis at x=4 x = -4 . This indicates a potential root or turning point where the function transitions from positive to negative or vice versa.
  • From the graph, it appears that the function is above the x-axis on both sides of x=4 x = -4 , except exactly at x=4 x = -4 , where it touches the x-axis.

Hence, the function f(x) f(x) is positive for x>4 x > -4 and for x<4 x < -4 . Note that exactly at x=4 x = -4 , the function is zero, not positive.

Therefore, the solution is: x>4 x > -4 or x<4 x < -4 .

In conclusion, the function f(x) f(x) is positive for these values of x x , except the point where it touches the x-axis.

The corresponding choice given the problem's options is:

x > -4 or x < -4

Answer

x > -4 or x < -4

Exercise #11

Find all values of x

where f(x) < 0 .

XXXYYY-4-4-4

Step-by-Step Solution

Let's analyze the graph to determine where f(x)<0 f(x) < 0 .

The process to follow is:

  • Identify the x-axis intersections (roots) where f(x)=0 f(x) = 0 .
  • Notice where the graph dips below the x-axis, indicating f(x)<0 f(x) < 0 .
  • The graph crosses and only touches the x-axis at x=4 x = -4 .
  • The graph lies below the x-axis both to the left and right of x=4 x = -4 .

From this analysis, the function f(x) f(x) is negative for all x x except at x=4 x = -4 , where it touches but doesn’t dip below the x-axis.

Therefore, the solution is that the function is negative for x>4 x > -4 or x<4 x < -4 .

Answer

x > -4 or x < -4

Exercise #12

Based on the data in the sketch, find for which X values the graph of the function f\left(x\right) > 0

XXXYYY000-2-2-2

Step-by-Step Solution

Based on the graph provided, we can see the entire function lies below the x-axis. Thus, there is no interval where f(x)>0 f(x) > 0 .

To solve this problem, here's what we observed:

  • Visual inspection of the graph reveals that it never crosses the x-axis from below.
  • Consequently, the function remains non-positive for all x-values visible, indicating it's non-positive overall within the range observable.

Therefore, the function has no domain where it is positive. Therefore, the solution is:

The function has no domain where it is positive

Answer

The function has no domain where it is positive

Exercise #13

Based on the data in the sketch, find for which X values the graph of the function f\left(x\right) > 0

XXXYYY111777444

Step-by-Step Solution

To determine the values of x x at which the function f(x)>0 f(x) > 0 , we analyze the graphically provided quadratic function. The function f(x) f(x) is represented as a parabola in the given diagram. We find the points where the parabola intersects the x-axis, marking critical points for determining sign changes in the function.

Upon examining the graph, we identify the x-intercepts at x=1 x = 1 and x=7 x = 7 . The function changes sign around these x-intercepts as follows:

  • For x<1 x < 1 , the graph is above the x-axis, implying f(x)>0 f(x) > 0 .
  • For 1<x<7 1 < x < 7 , the graph is below the x-axis, implying f(x)<0 f(x) < 0 .
  • For x>7 x > 7 , the graph is again above the x-axis, implying f(x)>0 f(x) > 0 .

Consequently, the solutions where f(x)>0 f(x) > 0 are at x<1 x < 1 and x>7 x > 7 . Comparing these results with the given answer options, option 3, which is x>7 x > 7 or x<1 x < 1 , corresponds precisely to our solution.

Therefore, the correct solution to the problem is x>7 x > 7 or x<1 x < 1 .

Answer

x > 7 or x < 1

Exercise #14

Based on the data in the diagram, find for which X values the graph of the function f\left(x\right) < 0

XXXYYY111777444

Step-by-Step Solution

To solve the problem of determining where f(x)<0 f(x) < 0 :

  • Step 1: Identify the x-intercepts of the graph, which are x=1 x = 1 and x=7 x = 7 .
  • Step 2: Examine the section of the graph between these intercepts. Since the graph dips below the x-axis between these values, f(x)<0 f(x) < 0 in that interval.

Therefore, the function is negative between the roots, i.e., 1<x<7 1 < x < 7 .

Thus, the solution to the problem is: 1<x<7 1 < x < 7 .

Answer

1 < x < 7

Exercise #15

Based on the data in the sketch, find for which X values the graph of the function f\left(x\right) > 0

XXXYYY222888555

Video Solution

Step-by-Step Solution

To solve this problem effectively, follow these steps:

  • Step 1: Identify where the parabola crosses the x-axis. These are the x-intercepts or roots. Let’s call these intercepts x1 x_1 and x2 x_2 .
  • Step 2: Since the question asks for f(x)>0 f(x) > 0 , we need to find where the graph is above the x-axis.
  • Step 3: Examine the sketch: The parabola dips below the x-axis after the first root and re-emerges above it until the second root, which is characteristic of a quadratic function.
  • Step 4: Thus, the function is positive between the two intercepts.

From the sketch, it is clear that the x-values where the function f(x)>0 f(x) > 0 are between the two intercepts, specifically (x1,x2)(x_1, x_2), which look like 22 and 88 on the graph.

Therefore, for this problem, the interval where f(x)>0 f(x) > 0 is 2<x<82 < x < 8.

The solution to this problem is 2<x<8 2 < x < 8 .

Answer

2 < x < 8

Exercise #16

Based on the data in the diagram, find for which X values the graph of the function f\left(x\right) < 0

XXXYYY222888555

Step-by-Step Solution

To solve for when f(x) < 0 on the graph, we follow these steps:

  • Step 1: Locate the x-intercepts, where the curve intersects the x-axis. These intercepts are x=2 x = 2 and x=8 x = 8 .

  • Step 2: Analyze the sections determined by these intercepts. The graph is below the x-axis to the left of x=2 x = 2 and to the right of x=8 x = 8 .

By visually inspecting the graph, it is evident that:

  • The function f(x) f(x) is below the x-axis (i.e., negative) for x < 2 and x > 8 .

Therefore, the solution to the problem is that the graph of the function is negative for x > 8 or x < 2 .

Answer

x > 8 or x < 2

Exercise #17

Based on the data in the diagram, find for which X values the graph of the function f\left(x\right) > 0

XXXYYY-2-2-2222000

Step-by-Step Solution

The problem is asking us to identify for which x x values f(x)>0 f(x) > 0 based on the graph provided, which seems to depict a quadratic function. Let's go step-by-step:

First, we need to determine the points where the function intersects the x-axis, which are the roots of the function. The graph shows these intersections at x=2 x = -2 and x=2 x = 2 . These are the points where the function is equal to zero, f(x)=0 f(x) = 0 .

Next, we observe the overall shape of the graph to understand where f(x)>0 f(x) > 0 (i.e., where the graph is above the x-axis). Typically for a quadratic function, which is a parabola, the parabola will be above the x-axis outside the roots if it opens upwards, and between the roots if it opens downwards, given that a(xx1)(xx2)=0 a(x - x_1)(x - x_2) = 0 with root analysis on a>0 a > 0 .

In the provided graph, the parabola appears to open upwards. Therefore, the function f(x) f(x) is positive when x x is less than the smaller root, 2 -2 , or greater than the larger root, 2 2 . This is a typical behavior for a quadratic function which opens upwards, where it takes negative values inside the range of its roots and positive values outside.

Conclusively, f(x)>0 f(x) > 0 for the intervals where x<2 x < -2 or x>2 x > 2 .

Therefore, the solution to the problem is x>2 x > 2 or x<2 x < -2 .

Answer

x > 2 or x < -2

Exercise #18

Based on the data in the diagram, find for which X values the graph of the function f\left(x\right) < 0

XXXYYY-2-2-2222000

Step-by-Step Solution

To solve the problem of finding for which x x values the function f(x)<0 f(x) < 0 , we proceed as follows:

First, we observe the provided graph of the function. Our goal is to identify the intervals on the x x -axis where the curve of the function is below the line y=0 y = 0 (the x-axis). These intervals represent where the function f(x) f(x) takes negative values.

Upon examining the graph, we notice that:

  • The curve descends below the x-axis starting once it crosses x=2 x = -2 .
  • It continues below the x-axis until it reaches x=2 x = 2 .
  • Therefore, the function is negative between these two points.

Based on the graph, the interval where f(x)<0 f(x) < 0 is from x=2 x = -2 to x=2 x = 2 . Thus, the correct mathematical statement for the values of x x where f(x)<0 f(x) < 0 is 2<x<2 -2 < x < 2 .

The correct choice from the options given is \(\text{2<x<2 -2 < x < 2 }\).

Therefore, the solution to the problem is 2<x<2 -2 < x < 2 .

Answer

-2 < x < 2

Exercise #19

Based on the data in the diagram, find for which X values the graph of the function f\left(x\right) > 0

XXXYYY-3-3-3333000

Step-by-Step Solution

First, we examine the provided graph of the quadratic function f(x) f(x) . The graph clearly shows the x-intercepts (where the function crosses the x-axis) at x=3 x = -3 and x=3 x = 3 .

Since the quadratic function appears to be a standard parabola opening upwards, the portion of the graph between these two x-intercepts will be above the x-axis, which means that f(x)>0 f(x) > 0 in this interval.

The intervals to the left of x=3 x = -3 and to the right of x=3 x = 3 will be where the graph lies below the x-axis, meaning f(x)<0 f(x) < 0 in those regions.

Thus, the graph shows that the function f(x) f(x) is positive between x=3 x = -3 and x=3 x = 3 . Therefore, the solution to the problem is:

3<x<3 -3 < x < 3

Answer

-3 < x < 3