Plotting Functions with Parameters: Linking function properties to its representation

Examples with solutions for Plotting Functions with Parameters: Linking function properties to its representation

Exercise #1

Does the parable

y=(x2)(x+1) y=(x-2)(x+1)

Is there a minimum or maximum point?

Video Solution

Step-by-Step Solution

To determine if the function y=(x2)(x+1) y = (x-2)(x+1) has a minimum or maximum point, we start by converting it from product form to standard form:

y=(x2)(x+1) y = (x-2)(x+1)

Expanding the expression:

y=x2+x2x2 y = x^2 + x - 2x - 2

Simplify:

y=x2x2 y = x^2 - x - 2

In standard form, y=x2x2 y = x^2 - x - 2 , the coefficient of x2 x^2 , which is a=1 a = 1 , is positive. A positive a a indicates the parabola opens upwards.

Since the parabola opens upwards, it has a minimal point (vertex) as its lowest point.

Therefore, the parabola y=(x2)(x+1) y = (x-2)(x+1) has a minimal point.

Answer

Minimal point

Exercise #2

Does the parable

y=x2+3x+9 y=-x^2+3x+9

Is there a minimum or maximum point?

Video Solution

Step-by-Step Solution

The quadratic function is given by y=x2+3x+9 y = -x^2 + 3x + 9 .

In the general quadratic form y=ax2+bx+c y = ax^2 + bx + c , the coefficient a a determines the parabola's orientation:

  • If a>0 a > 0 : The parabola opens upwards, indicating a minimum point.
  • If a<0 a < 0 : The parabola opens downwards, indicating a maximum point.

For this function, a=1 a = -1 . Since a<0 a < 0 , the parabola opens downwards.

Therefore, the function has a maximum point.

Thus, the correct answer is the function has a highest point.

Therefore, the solution to the problem is choice 2: Highest point.

Answer

Highest point

Exercise #3

Does the parable

y=x2+2x y=x^2+2x

Is there a minimum or maximum point?

Video Solution

Step-by-Step Solution

To determine whether the quadratic function y=x2+2x y = x^2 + 2x has a minimum or maximum point, we need to examine its structure and calculate the vertex.

Step 1: Identify the structure of the quadratic function.

The given function is y=x2+2x y = x^2 + 2x , which is a standard form quadratic function y=ax2+bx+c y = ax^2 + bx + c where a=1 a = 1 , b=2 b = 2 , and c=0 c = 0 .

Step 2: Calculate the vertex.

The vertex of a quadratic function is given by x=b2a x = -\frac{b}{2a} . Substituting the values of a a and b b into this formula gives:

x=22×1=1 x = -\frac{2}{2 \times 1} = -1 .

Substitute x=1 x = -1 back into the original equation to find the y-coordinate of the vertex:

y=(1)2+2(1)=12=1 y = (-1)^2 + 2(-1) = 1 - 2 = -1 .

Therefore, the vertex is at the point (1,1)(-1, -1).

Step 3: Determine if the vertex is a minimum or maximum.

Since the coefficient a=1 a = 1 is positive, the parabola opens upwards. This means that the vertex represents the lowest point on the graph, which is a minimum point.

Therefore, the solution to this problem is that the parabola has a minimal point.

Answer

Minimal point

Exercise #4

Does the parable

y=2x(x+1) y=-2x(x+1)

Is there a minimum or maximum point?

Video Solution

Step-by-Step Solution

To determine whether there is a minimum or maximum point in the quadratic function y=2x(x+1) y = -2x(x+1) , let's follow these steps:

  • Simplify the given function. Distribute the negative sign to expand the polynomial:

y=2x(x+1) y = -2x(x+1)

y=2x22x y = -2x^2 - 2x

  • Identify the coefficients of the quadratic equation in the form ax2+bx+c ax^2 + bx + c :
  • a=2 a = -2 , b=2 b = -2 , and c=0 c = 0 .
  • Since the coefficient of x2 x^2 , a a , is negative, the parabola opens downwards.

When a parabola opens downwards, it has a maximum point, as it reaches a peak value (the highest point) before descending.

Therefore, the quadratic function y=2x(x+1) y = -2x(x+1) has a maximum point.

Hence, the correct answer is that the parable has a highest point.

Answer

Highest point

Exercise #5

Does the parable

y=6xx2 y=6x-x^2

Is there a minimum or maximum point?

Video Solution

Step-by-Step Solution

To solve this problem, we need to determine whether the quadratic function y=6xx2 y = 6x - x^2 has a minimum or maximum point.

Firstly, let's identify the general form of the quadratic equation, which is y=ax2+bx+c y = ax^2 + bx + c . For our function, we have:

  • a=1 a = -1
  • b=6 b = 6
  • c=0 c = 0

The coefficient a=1 a = -1 is negative, indicating that the parabola opens downwards. A downward-opening parabola means that the function has a maximum point.

Next, we calculate the x-coordinate of the vertex, which gives the maximum point:

The formula for the x-coordinate of the vertex of a quadratic function ax2+bx+c ax^2 + bx + c is:

x=b2a x = -\frac{b}{2a}

Substituting the values of a a and b b into the vertex formula, we get:

x=62×1=62=3 x = -\frac{6}{2 \times -1} = -\frac{6}{-2} = 3

Thus, the x-coordinate of the vertex is x=3 x = 3 . We can substitute this back into the original equation to find the y-coordinate:

y=6(3)(3)2=189=9 y = 6(3) - (3)^2 = 18 - 9 = 9

Therefore, the vertex of the parabola is at (3,9) (3, 9) , and since the parabola opens downwards, this point represents the maximum point of the function.

We conclude that the quadratic function y=6xx2 y = 6x - x^2 reaches a highest point.

Answer

Highest point

Exercise #6

Does the parable

y=2x(x+3) y=2x(x+3)

Is there a minimum or maximum point?

Video Solution

Step-by-Step Solution

To solve this problem, follow these steps:

  • Step 1: Express the quadratic function in standard form. The given function is y=2x(x+3) y = 2x(x + 3) , which can be expanded to y=2x2+6x y = 2x^2 + 6x .
  • Step 2: Identify the coefficient of x2 x^2 . In this case, a=2 a = 2 .
  • Step 3: Determine the direction of the parabola. Since a=2 a = 2 is positive, the parabola opens upwards.
  • Step 4: Conclude that the vertex represents the lowest point, which is the minimum point.

Given that the coefficient a a is positive, the parabola opens upwards, indicating that the vertex is a minimum point.

Therefore, the solution to this problem is minimal point.

Answer

Minimal point

Exercise #7

Does the parable

y=(x+1)(x1) y=-(x+1)(x-1)

Is there a minimum or maximum point?

Video Solution

Step-by-Step Solution

To solve this problem, let's analyze the function step-by-step:

Step 1: Expand the given quadratic function.
The function provided is y=(x+1)(x1) y = -(x+1)(x-1) . We rewrite it by expanding:

y=(x21)=x2+1 y = -(x^2 - 1) = -x^2 + 1 .

Step 2: Determine the direction of the parabola.
The standard form y=ax2+bx+c y = ax^2 + bx + c indicates that the parabola opens upwards if a>0 a > 0 and downwards if a<0 a < 0 . Here, the value of a a is 1-1, which means the parabola opens downwards.

Step 3: Identify the vertex type.
Since the parabola opens downwards, the vertex represents the highest point on the graph, which is a maximum.

Therefore, the parabola has a maximum point. The correct choice is:

Choice 2: Highest point

Thus, we conclude that the given quadratic function has a maximum point.

Answer

Highest point

Exercise #8

Does the parable

y=(x+1)(x1) y=(x+1)(-x-1)

Is there a minimum or maximum point?

Video Solution

Step-by-Step Solution

To solve this problem, follow these steps:

  • Step 1: Expand the quadratic function.
  • Step 2: Determine the nature based on the leading coefficient.

Step 1: Expand the quadratic function:

The given function is y=(x+1)(x1) y = (x+1)(-x-1) .

Expanding this, we have:

y=(x+1)(x1)=x(x1)+1(x1)=x2xx1=x22x1 y = (x+1)(-x-1) = x(-x-1) + 1(-x-1) = -x^2 - x - x - 1 = -x^2 - 2x - 1

Step 2: Determine the nature using the leading coefficient:

The quadratic function is y=x22x1 y = -x^2 - 2x - 1 .

Here, the leading coefficient a=1 a = -1 . Since the leading coefficient is negative, the parabola opens downwards.

Therefore, the quadratic function has a highest point, or a maximum.

Thus, the solution to the problem is that the quadratic function has a highest point.

Answer

Highest point