How do you factor # x^4-8x^2-9#?

1 Answer

Answer:

#(x^2+1)(x+3)(x-3)#

Explanation:

first lets substitute #x^2 = t#
we get #t^2 - 8*t - 9#
now split the middle term #t^2 + t - 9*t - 9#
factorize now #t(t+1) -9(t+1)#
now we get #(t+1)(t-9)#
now substitute back #t=x^2#
we get #(x^2+1)(x^2-9)#
we can still factorize the #x^2-9# term
so we get #(x^2+1)(x+3)(x-3)#
this is the answer