Question

(x^2 + 3)^2 - 6(x^2 + 3) = 7

Answer 1

let (x^2 + 3) = t and solve for t
then solve (x^2 + 3 = t for all values of t

Answer 2

A sub looks good, maybe a difference of squares, too.

Answer 3

Oh, that's stupid, it's not squared, lol..

Answer 4

x^4-16=0
(X^2+4)(x^2-4)=0
(x^2+4)(x-2)(x+2)
x=2i,-2i,2,-2

Answer 5

dont forget to resub in t and you will get my answer