1) y²+3y-4y-12+y²+2y+1-49+y²= 3y²+y-60
2) 7ab(3a+4b)
(6m-10√n)*(6m+10√n)
(5+ab)(25-5ab+a²b²)
5x(x²-y²)= 5x(x-y)(x+y)