Question 1082743
 {{{(x^4 -y)^5}}}

= {{{(x^4 -y)(x^4 - y)(x^4 -y)(x^4- y)(x^4 -y)}}}

= {{{(x^8 -2x^4y + y^2)(x^8 - 2x^4*y + y^2)(x^4- y)}}}

= {{{(x^16 - 4x^12*y + 6x^8*y^2 - 4 x^4*y^3 + y^4)(x^4 - y)}}}

= {{{x^20 - 5x^16*y + 10x^12*y^2 - 10x^8*y^3 + 5x^4*y^4 - y^5}}}