Which statement is true about the quadratic function f ( x ) = − 4 x 2 − 8 x + 4 ?

Question

A)the range is less than or equal to 4

B)The range is less than or equal to 8

C)The domain is greater than or equal to 0

D)The domain is greater than or equal to -1

please explain how im even supposed to know this?!?! Where am i going to find the domain or range in this?

Answer 1

If you factor the equation -4x^2 - 8x + 4 you get

-4(x^2 + 2x - 1).

The domain can be any real number, so C and D are eliminated

if x is 0, then f(x) = 4

if x is 1, then f(x) = -8

if x is 2, then f(x) = -28

if x is -1, then f(x) = 8

if x is -2, then f(x) = 4

thus the answer is B as the range is less than or equal to 8