which functions have a range of [-2,infinity)?

Question

A. f(x)=2(x+2)(x-1) B.f(x)=(x-1)2 -2 C.f(x)= (x-1)(x+3) D. f(x)=-(x+3)2 E. f(x)=-2x2-8x+3 F. f(x)=1/2x2-2

Answer 1

This function is a positive quadratic with a vertex of (h, k), since the parabola shoots upward.

 

where the vertex form of a quadratic is

 

f(x) = a(x - h)² + k

 

with       k = -2

 

 

Use this fact to find your functions.  There could be more than one.