How do you factor 5x^3 + 40y^65x3+40y6?

1 Answer
May 18, 2015

You can use a formula for a sum of cubes:
a^3+b^3=(a+b)*(a^2-ab+b^2)a3+b3=(a+b)(a2ab+b2)

Notice that 40y^6=5*8*y^6=5*2^3*(y^2)^3=5*(2y^2)^340y6=58y6=523(y2)3=5(2y2)3

Using the above formula for a=xa=x and b=2y^2b=2y2 and factoring out constant 55, we get:
5x^3+40y^6 =5x^3+5(2y^2)^3=5(x+2y^2)(x^2-2xy^2+4y^4))5x3+40y6=5x3+5(2y2)3=5(x+2y2)(x22xy2+4y4))