Đáp án:
Giải thích các bước giải:
`a) x(a + b) +a+b`
`= x(a + b) + (a + b)`
` =(x + 1)(a + b)`
`b) 3a^2x - 3a^2y + abx - aby`
`=3a^2(x - y) + ab(x - y)`
`=(x - y)(3a^2 + ab)`
`=(x - y)a(3a + b)`
`c) ax + bx+ cx+ 2a + 2b+2c`
`=a(x + 2) + b(x + 2) + c(x + 2)`
`=(x + 2)(a + b + c)`
`d)a^2 - b^2 - 4a + 4b`
`=(a- b)(a + b) - 4(a - b)`
`=(a - b)(a + b + 4)`
`e)(xy+4)^2 - (2x+2y)^2`
`=(xy + 4 - 2x - 2y)(xy + 4 + 2x + 2y)`
`=[xy - 2x - 2y + 4][xy + 2x + 2y + 4]`
`=[x(y - 2) - 2(y - 2)][x(y + 2) + 2( y +2)]`
=`(X - 2)(y - 2)(x + 2)(y + 2)`