Đáp án+Giải thích các bước giải:
`3)x^4-4x^3+4x^2`
`=(x^2-2x)^2`
`=[x(x-2)]^2`
`=x^2(x-2)^2`
`5)5x^3-10x^2+5x`
`=5(x^3-2x^2+x)`
`=5x(x-1)^2`
`7)8x^2y-8xy+2x`
`=2x(4xy-4y+1)`
`9)2x^3-12x^2+18x`
`=2(x^3-6x^2+9x)`
`=2x(x-3)^2`
`11)5x^2y-35xy+60y`
`=5y(x^2-7x+12)`
`=5y(x^2-3x-4x+12)`
`=5y(x-3)(x-4)`
`13)3x^2-3xy-5x+5y`
`=3x(x-y)-5(x-y)`
`=(x-y)(3x-5)`
`15)6x^2y^2+4xy^2-12x^3y`
`=2xy(3xy+2y-6x^2)`
`17)x^2+4x-2xy-4y+y^2`
`=4x-4y+x^2-2xy+y^2`
`=4(x-y)+(x-y)^2`
`=(x-y)(x-y+4)`
`19)14x^2y-21xy^2+28x^2y^2`
`=7xy(2x-3y+4xy)`
`6)x^5-x^4+x^3-x^2+x-1`
`=x^4(x-1)+x^2(x-1)+x-1`
`=(x-1)(x^4+x^2+1)`
`=(x-1)(x^4+2x^2+1-x^2)`
`=(x-1)[(x^2+1)^2-x^2]`
`=(x-1)(x^2-x+1)(x^2+x+1)`
`10)x^3-y^3+2x^2+2xy+2y^2`
`=(x-y)(x^2+xy+y^2)+2x^2+2xy+2y^2`
`=(x^2+xy+y^2)(x-y+2)`
`14)49(y-4)^2-9y^2-36y-36`
`=[7(y-4)]^2-(3y+6)^2`
`=[7(y-4)-3y-6][7(y-4)+3y+6]`
`=(7y-28-3y-6)(7y-28+3y+6)`
`=(4y-34)(10y-22)`
`=4(2y-17)(5y-11)`
