# [ASK] Make x and y the Subjects

#### Monoxdifly

$$\displaystyle x^3-3xy^2=a$$
$$\displaystyle 3x^2y-y^3=b$$
make a formula using a and b for x and y.

What I've done:
$$\displaystyle x^3-3xy^2+3x^2y-y^3=a+b$$
$$\displaystyle x^3+3x^2y-3xy^2-y^3=a+b$$
$$\displaystyle (x-y)(x^2+4xy+y^2)=a+b$$
I don't know what to do from here. Any hints?

#### romsek

MHF Helper
The answer is looking like a real mess.