Đáp án+Giải thích các bước giải:
`1) 6x^2-2x(3x+3/2)`
`=6x^2-6x^2-3x`
`=-3x`
`2) (x^2+4x)(2x^3-8x^2+32)`
`=x^2 . (2x^3-8x^2+32)+4x.(2x^3-8x^2+32)`
`=2x^5-8x^4+32x^2+8x^4-32x^3+128x`
`=2x^5-(8x^4-8x^4)-32x^3+32x^2+128x`
`=2x^5-32x^3+32x^2+128x`
`3) (5x^3-x^2+2x-3)(4x^2-x+2)`
`= 4x^2 . (5x^3-x^2+2x-3)-x. (5x^3-x^2+2x-3)+2.(5x^3-x^2+2x-3)`
`=20x^5-4x^4+8x^3-12x^2-5x^4+x^3-2x^2+3x+10x^3-2x^2+4x-6`
`=20x^5+(-4x^4-5x^4)+(8x^3+x^3+10x^3)-(12x^2+2x^2+2x^2)+(4x+3x)-6`
`=20x^5-9x^4+19x^3-16x^2+7x-6`
`4) (25x^2+10xy+4y^2)(5x-2y)`
`=5x.(25x^2+10xy+4y^2)-2y.(25x^2+10xy+4y^2)`
`=125x^3+50x^2y+20xy^2-50x^2y-20xy^2-8y^3`
`=125x^3-(50x^2y-50x^2y)+(20xy^2-20xy^2)-8y^3`
`=125x^3-8y^3`
`5) 3x^2-2x(5-1,5x)+10`
`=3x^2-10x+3x^2+10`
`=6x^2-10x+10`
`6) 2x^4-5x^3+4x^2(-1/2x^2+5/4x+1)`
`=2x^4-5x^3-2x^4+5x^3+4x^2`
`=4x^2`
`7) 7x(4y-x)+4y(y-7x)-2(2y^2-3,5x)`
`=28xy-7x^2+4y^2-28xy-4y^2+7x`
`=-7x^2+7x`
`8) 1/2x^3(4x^2-6x+1/2)-(x^3-1/2x^2-1/8x)2x^2`
`=2x^5-3x^4+1/4x^3-2x^5+x^4+1/4x^3`
`=-2x^4+1/2x^3`
`9) (x^2-2)(x^2+x-1)-x(x^3+x^2-3x-2)`
`=x^4+x^3-x^2-2x^2-2x+2-x^4-x^3+3x^2+2x`
`=2`
`10) (3x+2y-1)(x+5)(x-2)2y`
`= [(3x+2y-1)(x+5)][(x-2)2y]`
`=(3x^2+15x+2xy+10y-x-5)(2xy-4y)`
`=(3x^2+14x+2xy+10y-5)(2xy-4y)`
`=2xy(3x^2+14x+2xy+10y-5)-4y(3x^2+14x+2xy+10y-5)`
`=6x^3y+28x^2y+4x^2y^2+20xy^2-10xy-12x^2y-56xy-8xy^2-40y^2+20y`
`=6x^3y+16x^2y+4x^2y^2+12xy^2-66xy-40y^2+20y`
