Question

Làm tính nhân :

a ) \(3x\left(5x^2-2x-1\right)\)

b ) \(\left(x^2+2xy-3\right)\left(-xy\right)\)

 

Answer 1

Siêu dễ :

a )  \(3x\left(5x^2-2x-1\right)\)

\(=3x.5x^2-3x.2x-3x.1\)

\(=15x^3-6x^2-3x\)

b ) \(\left(x^2+2xy-3\right)\left(-xy\right)\)

\(=-xy.x^2-xy.2xy+xy.3\)

\(=-x^3y-2x^2y^2+3xy\)

Answer 2

a)

\(3x\left(5x^2-2x-1\right)\)

\(=15x^3-6x^2-3x\)

b)

\(\left(x^2+2xy-3\right)\left(-xy\right)\)

\(=-x^3y-2x^2y^2+3xy\)