Question

Use the graphing calculator to graph the quadratic function y = 2x2 + 2x – 40. What are the zeros of the function?

4 and –5
–4 and 5
–5 and –40
4 and –40

Answer 1

First divide by 2: x^2 + x − 20 = 0, which factors as (x + 5)(x − 4) = 0.
So the zeros are x = −5 and x = 4.

Answer: 4 and −5.