mọi người giúp mình với 1 tiếng nữa đi học r ( hơi mờ mọi người thông cảm)

`vansociu`

`a) xy+yz+3x+3z`

`=y(x+z)+3(x+z)`

`=(x+z)(y+3)`

`b)xy-xz+y-z`

`=x(y-z)+y-z`

`=(y-z)(x+1)`

`c) 11x+11y-x²-xy`

`=11(x+y)-x(x+y)`

`=(11-x)(x+y)`

`d) x²-xy-8x+8y`

`=x(x-y)-8(x-y)`

`=(x-8)(x-y)`

`e) x²-8x-y²+16`

`=(x²-8x+16)-y²`

`=(x-4)²-y²`

`=(x-4-y)(x-4+y)`

`f) x²+2xy-xz+y²`

`=(x²+2xy+y²)-xz`

`=(x+y)²-xz`

`g) 25-4x²-4xy-y²`

`=25-[(2x)²-2.2xy-y²]`

`=5²-(2x-y)²`

`=(5-2x+y)(5+2x-y)`

`h) x²+6x+5`

`=x²+x+5x+5`

`=x(x+1)+5(x+1)`

`=(x+1)(x+5)`

`k) x²-5x-6`

`=x²-6x+x-6`

`=x(x-6)+(x-6)`

`=(x-6)(x+1)`

`l) x^4+4`

`=(x²)²+2²`

`=(x²+2)-4x²`

`=(x²+2)-(2x)²`

`=(x²-2x+2)(x²+2x+2)`