BÀI 2
`a) 2ax+8ay`
`=2a(x+4y)`
`b) x²-12x+36`
`=x²-2.6x+6²`
`=(x-6)²`
`c)x²-y²+10x-10y`
`=(x²-y²)+(10x-10y)`
`=(x-y)(x+y)+10(x-y)`
`=(x-y)(x+y+10)`
BÀI 1
`a) x²+x(2-x)+5x`
`=x²+2x-x²+5x`
`=2x+5x=7x`
`b) (x-3)²-x²+10x-7`
`=(x-3+x)(x-3-x)+10x-7`
`=x²-3x-x²-3x+9+3x+x²-3x-x²+10x-7`
`=-3x-3x+9+3x-3x+10x-7`
`=4x+9-7`
`=4x+2`
`=2(2x+1)`
$c)\dfrac{4}{x+1}$ +$\dfrac{4}{x(x+1)}$
$=\dfrac{4x}{x(x+1)}$+$\dfrac{4}{x(x+1)}$
$=\dfrac{4x+4}{x(x+1)}$
$=\dfrac{4(x+1)}{x(x+1)}$
$=\dfrac{4}{x}$
