Math Question

This is the last problem for my math class and I can't figure out how to work it for the life of me. I assumed you just square the f(a), but it says it's wrong.

If f(x) = 2x2 - x + 4, find the following. Find [f(a)]^2

By 2x2, do you mean 2x^2?

(2x^2-x+4)(2x^2-x+4)
4x^4-2x^3+8x^2-2x^3+x^2-4x+8x^2-4x+16
4x^4 -2x^3-2x^3 +8x^2+x^2+8x^2 -4x-4x +16

4x^4 -4x^3 +17x^2 -8x +16

Then you could "simplify" it quite a few ways if you wanted to grouping the coefficients.  Does it just say it's wrong, or do you know what it should be?

[f(a)]^2
x -> a

Ya, thats what I meant. Thanks for the help, I finally got that one now :)