Question

What is the range of the function y = 2x2 + x - 1 when the domain is {-2, -1, 0, 1}?

Answer 1

If we transform each of the points we have

$f(-2)=2(-2)^2+(-2)-1 = 8-2-1=5$

$f(-1)=2(-1)^2+(-1)-1 = 2-1-1=0$

$f(0)=2(0)+0-1=0+0-1=-1$

$f(1)=2(1)^2+(1)-1 = 2+1-1=2$

The range is simply the set of all possible outputs.