Question

What is the domain and range of the quadratic equation y = –2x2 – 32x – 126?

Answer 1

All quadratic equations of this type have domains of "all real numbers." To find the range, it is sometimes easier to put it into vertex form first to more easily find the minimum or maximum.

Answer 2

i got -8 & 2 but im not sure which is the right answer or if they are greater than or less than y

Answer 3

How did you get -8 and 2? There should be only a single number for the y-coordinate of the vertex.

Answer 4

(Just worked it out myself), I see, -8 and 2 are the x and y coordinates of the vertex. You only need to consider the y coordinate for the range.
Does the parabola open up or down? Do you know how to tell?

Answer 5

it opens downward

Answer 6

i know how to tell if the parabola is shifted left or right or is upward downward narrow or wide i just forgot how to find the range

Answer 7

Good. Then y=2 is a maximum.

Answer 8

You can express the range either with an inequality: y≤2 or using interval notation: (-∞,2]

Answer 9

oh ok thank you:)