帮做几道因式分解题2

1)a^4x^(n+3)-x^(n-1)
=a^4x^(n-1+4)-x^(n-1)
=x^(n-1)(a^4x^4-1)
=x^(n-1)(a^2x^2+1)(ax+1)(ax-1)

(2)(x^2+2x-18)(x^2-2x)+45
=[x^2+2x][x^2-2x]-18[x^2-2x]+45
=x^4-4x^2-18x^2+36x+45
=[x^4-18x^2+81]-4[x^2-9x+9]
=[x^2-9]^2-4[x^2-9-9x+18]
下面自己再算吧，检查原题一下数字有没有错。

it is not interesting