Answer :

f(x)=(x+5)²(x-1)

=(x-1)(x²+10x+25)

=x²(x-1)+10x(x-1)+25(x-1)

=x³-x²+10x²-10x+25x-25

=x³+9x²+15x-25
[tex](x+5)^2(x-1)=\\ (x^2+10x+25)(x-1)=\\ x^3-x^2+10x^2-10x+25x-25=\\ x^3+9x^2+15x-25[/tex]