Quadratic Function Practice Problems & Solutions

Master quadratic functions with step-by-step practice problems. Learn to find vertices, intercepts, and graph parabolas with confidence.

📚Practice Your Quadratic Function Skills
  • Find the vertex of parabolas using the vertex formula
  • Determine if a parabola opens upward or downward
  • Calculate x and y intercepts of quadratic functions
  • Identify increasing and decreasing intervals from graphs
  • Solve quadratic equations using factoring and quadratic formula
  • Graph minimum and maximum parabolas accurately

Understanding Function

Complete explanation with examples

Function

What is a function?

A function is an equation that describes a specific relationship between XX and YY.
Every time we change XX, we get a different YY.

Linear function –

Looks like a straight line, XX is in the first degree.

Quadratic function –

Parabola, XX is in the square.

Detailed explanation

Practice Function

Test your knowledge with 28 quizzes

Given the linear function of the drawing.

What is the negative domain of the function?

xy

Examples with solutions for Function

Step-by-step solutions included
Exercise #1

Look at the linear function represented in the diagram.

When is the function positive?

–8–8–8–7–7–7–6–6–6–5–5–5–4–4–4–3–3–3–2–2–2–1–1–1111222333444555666777888–5–5–5–4–4–4–3–3–3–2–2–2–1–1–1111222333000

Step-by-Step Solution

The function is positive when it is above the X-axis.

Let's note that the intersection point of the graph with the X-axis is:

(2,0) (2,0) meaning any number greater than 2:

x>2 x > 2

Answer:

x>2 x>2

Video Solution
Exercise #2

Look at the function shown in the figure.

When is the function positive?

xy-4-7

Step-by-Step Solution

The function we see is a decreasing function,

Because as X increases, the value of Y decreases, creating the slope of the function.

We know that this function intersects the X-axis at the point x=-4

Therefore, we can understand that up to -4, the values of Y are greater than 0, and after -4, the values of Y are less than zero.

Therefore, the function will be positive only when

X < -4

 

Answer:

4>x -4 > x

Video Solution
Exercise #3

What is the solution to the following inequality?

10x43x8 10x-4≤-3x-8

Step-by-Step Solution

In the exercise, we have an inequality equation.

We treat the inequality as an equation with the sign -=,

And we only refer to it if we need to multiply or divide by 0.

 10x43x8 10x-4 ≤ -3x-8

We start by organizing the sections:

10x+3x48 10x+3x-4 ≤ -8

13x48 13x-4 ≤ -8

13x4 13x ≤ -4

Divide by 13 to isolate the X

x413 x≤-\frac{4}{13}

Let's look again at the options we were asked about:

Answer A is with different data and therefore was rejected.

Answer C shows a case where X is greater than413 -\frac{4}{13} , although we know it is small, so it is rejected.

Answer D shows a case (according to the white circle) where X is not equal to413 -\frac{4}{13} , and only smaller than it. We know it must be large and equal, so this answer is rejected.

 

Therefore, answer B is the correct one!

Answer:

Video Solution
Exercise #4

For the function in front of you, the slope is?

XY

Step-by-Step Solution

To solve this problem, we need to determine the slope of the line depicted on the graph.

First, understand that the slope of a line on a coordinate plane indicates how steep the line is and the direction it is heading. Specifically:

  • A positive slope means the line rises as it goes from left to right.
  • A negative slope means the line falls as it goes from left to right.

Let's examine the graph given:

  • We see that the line starts at a higher point on the left and descends to a lower point on the right side.
  • As we move from the left side of the graph towards the right, the line goes downwards.

This downward trajectory clearly indicates a negative slope because the line is declining as we move horizontally left to right.

Therefore, the slope of this function is Negative.

The correct answer is, therefore, Negative slope.

Answer:

Negative slope

Video Solution
Exercise #5

For the function in front of you, the slope is?

XY

Step-by-Step Solution

To determine the slope of the line shown on the graph, we perform a visual analysis:

  • We examine the orientation of the line from left to right.
  • The red line starts at a higher point on the left and descends to a lower point on the right.
  • This indicates a downward movement, which corresponds to a negative slope.

Therefore, by observing the direction of the line, we conclude that the slope of the function is negative. This positional evaluation confirms that the correct answer is negative slope.

Answer:

Negative slope

Video Solution

Frequently Asked Questions

How do I find the vertex of a quadratic function?

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Use the vertex formula X = -b/(2a) to find the x-coordinate, then substitute this value back into the original equation to find the y-coordinate. You can also use two symmetrical points and find their midpoint.

What's the difference between minimum and maximum parabolas?

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A minimum parabola (smiling) opens upward when a > 0, with the vertex as the lowest point. A maximum parabola (sad) opens downward when a < 0, with the vertex as the highest point.

How do I find where a parabola crosses the x-axis?

+
Set y = 0 in the quadratic equation and solve for x using factoring, completing the square, or the quadratic formula. The solutions are your x-intercepts.

What does the coefficient 'a' tell me about a quadratic function?

+
The coefficient 'a' determines the parabola's direction and width. If a > 0, it opens upward (minimum). If a < 0, it opens downward (maximum). Larger |a| values make narrower parabolas.

How do I determine increasing and decreasing intervals?

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For minimum parabolas: decreasing for x < vertex x-value, increasing for x > vertex x-value. For maximum parabolas: increasing for x < vertex x-value, decreasing for x > vertex x-value.

What's the standard form of a quadratic function?

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The standard form is y = ax² + bx + c, where 'a' cannot equal zero. This form makes it easy to identify the y-intercept (c) and calculate the vertex using formulas.

How do I find the y-intercept of a quadratic function?

+
Substitute x = 0 into the equation. The y-intercept is simply the constant term 'c' in the standard form y = ax² + bx + c.

Why is understanding parabolas important in real life?

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Parabolas model many real-world situations like projectile motion, satellite dishes, bridge arches, and profit optimization in business. Understanding their properties helps solve practical problems.

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