Đáp án:
`e, 18x^2 (3 + x) + 3(x + 3)`
`= (x + 3)(18x^2 + 3)`
`= (x + 3)(6x^2 + 1).3`
`b, (x - 3)^3 + 3 - x`
`= (x - 3)^3 - (x - 3)`
`= (x - 3)[(x - 3)^2 - 1]`
`= (x - 3)(x - 3 - 1)(x - 3 + 1)`
`= (x - 3)(x - 4)(x - 2)`
`h, 14x^2 y - 21xy^2 + 28x^2 y^2`
`= 7xy.2x - 7xy.3y + 7xy.4xy`
`= 7xy(2x - 3y + 4xy)`
`i, 7x(x - y) - (y - x)`
`= 7x(x - y) + (x - y)`
`= (x - y)(7x + 1)`
`k, 10x(x - y) - 8y(y - x)`
`= 10x(x - y) + 8y(x - y)`
`= (x - y)(10x + 8y)`
`= (x - y)(5x + 4y).2`
`= 2(x - y)(5x + 4y)`