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Range of a quadratic equation

Introduction

In this article, we'll practice finding the range of y-values of quadratic equations in vertex form, such as y=2(x+3)2+7. To do this article, you should already know how to graph parabolas.

Step-by-step practice problem

Let's breakdown how to find the range of y=5(x2)2+3 without seeing the graph.
Step 1: Find the y-coordinate of the vertex of the parabola.
  • Your answer should be
  • an integer, like 6
  • a simplified proper fraction, like 3/5
  • a simplified improper fraction, like 7/4
  • a mixed number, like 1 3/4
  • an exact decimal, like 0.75
  • a multiple of pi, like 12 pi or 2/3 pi

Step 2: Does the parabola open up or down?
Choose 1 answer:

Step 3: Is the y-coordinate of the vertex a minimum or a maximum?
Choose 1 answer:

What is the range of the parabola's y-values?
Write an inequality in terms of y.

Practice problem 1

What is the range of possible y-values for y=12(x3)2+2?
Write an inequality in terms of y.

Practice problem 2

What is the range of possible y-values for y=7(x+3)26?
Write an inequality in terms of y.

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