The function $f(x)$ is defined only on domain $[-1,2]$, and is defined on this domain by the formula f(x) = 2x^2-8x+1. What is the range of $f(x)$? Express your answer as an interval or as a union of intervals.
2(-1)^2 -8(-1) + 1 = 11
2(2)^2 - 8(2) + 1 = -7
The function is continuous on [ -1, 2] so the range is [ -7 , 11 ]