Question

Factor 40x^3-5y^3 COMPLETELY

Answer 1

$40x^3-5y^3=5(8x^3-y^3)=5[(2x)^3-y^3]\\\\use:a^3-b^3=(a-b)(a^2+ab+b^2)\\\\=5(2x-y)[(2x)^2+2xy+y^2]=5(2x-y)(4x^2+2xy+y^2)$