Question

b1: tính

a)      (4x - 7) . (5x² + 6xy - 3y)

b)      - 4xy² ( 2y² - 3xy + 5x²y)

c)       ( 5x + 3x + 1). (2x²y - xy)

 

Answer 1

`a)(4x-7)(5x^2+6xy-3y)`

`=20x^3+24x^2y-12xy-35x^2-42xy+21y`

`=20x^3+24x^2y-54xy-35x^2+21y`

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`b)-4xy^2(2y^2-3xy+5x^2y)`

`=-8xy^4+12x^2y^3-20x^3y^3`

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`c)(5x+3x+1)(2x^2y-xy)`

`=(8x+1)(2x^2y-xy)`

`=16x^3y-8x^2y+2x^2y-xy`

Answer 2

\(\text{a},=20x^3-35x^2+24x^2y-42xy-12xy+21y=20x^3-35x^2+24x^2y-54xy+21y\\ b,=-8xy^4+12x^2y^3-20x^3y^3\\ c,=10x^3y-5x^2y+6x^3y-3x^2y+2x^2y-xy=16x^3y-6x^2y-xy\)