3x(x+y+c)-3y(x-y-c)-3c(x+y-c)

Question

3x(x+y+c)-3y(x-y-c)-3c(x+y-c)

Answer 1

3x²+3xy+3xc-3xy+3y²+3yc-3xc-3yc+3c²=3x²+3y²+3c²

Answer 2

3x²+3xy+3xc-3xy+3y²+3cy-3cx-3cy+3c²=3x²+3y²+3c²=3(x²+y²+c²)