Câu trả lời:

a) 2x(x-3y)+3y(2x+5y)

=2x²-6xy+6xy+15y²

=2x²+15y²

b)(5x-3y)(2x+y)-x(10x-y)

=10x²+5xy-6xy-3y²-10x²+xy

=0

c)(x-y)(x²+xy+y²)-(x+y)(x²-xy+y²)

=x³-y³-(x³+y³)

=x³-y³-x³-y³

=-2y³