Bài 1:
`a,5x(x-1)-3x(x-1)`
`=(x-1)(5x-3x)`
`=(x-1)2x`
`b,(3x+1)²-(x+1)²`
`=(3x+1+x+1)(3x+1-x-1)`
`=4x(2x+1)`
`c,5x²+5xy-x-y`
`=(5x²+5xy)-(x+y)`
`=5x(x+y)-(x+y)`
`=(x+y)(5x-1)`
`d,x³+x²-2x-8`
`=x²(x-2)+3x(x-2)+4(x-2)`
`=(x-2)(x³+3x+4)`
Bài 2:
`a,x²+4x-5`
`=x²+5x-x-5`
`=(x+5)(x-1)`
`b,x²-6x+5`
`=x²-x-5x+5`
`=x(x-1)-5(x-1)`
`=(x-1)(x-5)`
`c,x²+6x-5`
`=(x²+6x+9)-14`
`=(x+3-\sqrt[14] )(x+3+\sqrt[14])`
`d,x²+x-2`
`=x²+2x-x-2`
`=x(x+2)-(x+2)`
`=(x+2)(x-1)`
`e,x²-5x+6`
`=x²-2x-3x+6`
`=(x-2)(x-3)`
`f,x²+3x-4`
`=x²+4x-x-4`
`=x(x+4)-(x+4)`
`=(x+4)(x-1)`
`g, 2x²-6x+8`
`=2(x²-3x+4)`
`h,3x²-5x+2`
`=3x²-3x-2x+2`
`=(x-1)(3x-2)`
`i,4x²+3x-7`
`=4x²+7x-4x-7`
`=x(4x+7)-(4x+7)`
`=(4x+7)(x-1)`
$@Race2k53$
Xin hay nhất !
