Hey Guys,

I am a bit confused on what to do for this problem. If I can get some help I'd appreciate it.

Suppose that f(x) = x^{4 }+ 7x^{2}+ 12. Find the values of x such that

a. f(x) = 12

b. f(x) = 6

I figured part b already but I am having trouble on part (a) which is

12 = x^{4 }+ 7x^{2}+ 12

-12 -12

Now I'm left with x^{4 + }7x^{2 }

I use "Let u = x^{2}, Let u^{2 = }x^{4}^{"}

u^{2 + }u

Do I get a third term by completing the square method? I am lost with this step.