Question

Thực hiện phép tính sau:
a)6xy.(2x²-\(\dfrac{2}{3}\)xy+\(\dfrac{1}{2}\)y²)
b)(x+3).(x²+3x-5)-x.(x-2)²

Answer 1

\(a,=12x^3y-4x^2y^2+3xy^3\\ b,=x^3+3x^2-5x+3x^2+9x-15-x^3-4x^2+4x\\ =2x^2+8x-15\)

Answer 2

b: Ta có: \(\left(x+3\right)\left(x^2+3x-5\right)-x\left(x-2\right)^2\)

\(=x^3+3x^2-5x+3x^2+9x-15-x^3+4x^2-4x\)

\(=10x^2-15\)