## Intermediate Algebra for College Students (7th Edition)

$(x^{2}-6)(x^{2}+1)$
Substituting $x^{2}=t$, the trinomial becomes quadratic, $t^{3}-5t-6=$ ... Searching for two factors of $-6$ whose sum is $-5,$ we find$\qquad-6$ and $+1$ $=(t-6)(t+1)$ ... bring back x = $(x^{2}-6)(x^{2}+1)$