Question

Thực hiện các phép nhân:

a) \(\left( {x - y} \right)\left( {x - 5y} \right)\)                                              

b) \(\left( {2x + y} \right)\left( {4{x^2} - 2xy + {y^2}} \right)\)

Answer 1

`a, (x-y)(x-5y)`

`= x^2 - xy - 5xy + 5y^2`

`= x^2 - 6xy + 5y^2`

`b, (2x+y)(4x^2 -2xy + y^2)`

`= (2x)^3 + y^3`

`= 8x^3 + y^3`

Answer 2

a) \(\left(x-y\right)\left(x-5y\right)\)

\(=x^2-5xy-xy+5y^2\)

\(=x^2-6xy+5y^2\)

b) \(\left(2x+y\right)\left(4x^2-2xy+y^2\right)\)

\(=8x^3-4x^2y+2xy^2+4x^2y-2xy^2+y^3\)

\(=8x^3+y^3\)