Question

3x'-5x-12(n-1)n(n+1)(n+2)+1帮算下,x'是x的二次方(n-1)n(n+1)(n+2)+1二楼做

Answer 1

3x'-5x-12

=(3x+4)(x-3)

补充:(n-1)n(n+1)(n+2)+1

=n^4+2n^3-n^2-2n+1

=n^4+2n^3-n-(n^2+n-1)

=n^2(n^2+n-1+1)+n^3-n-(n^2+n-1)

=(n^2+n-1)*(n^2-1)+n^2+n^3-n

=(n^2+n-1)*(n^2-1)+n*(n^2+n-1)

=(n^2+n-1)*(n^2+n-1)

=(n^2+n-1)^2