Question

thanks :)

Answer 1

\[(5C0) x^5(-3)^0+(5C1)x^4(-3)^1+(5C2)x^3(-3)^2+(5C3)x^2(-3)^3\] \[+(5C4)x^1(-3)^4+(5C5)x^0(-3)^5\]

Which simplified gives \[x^5-15x^4+90x^3-270x^2+405x-243\]

Answer 2

^^ That is using binomial Theorem.