Đáp án:
1 .`x^3 - 5x^2y - 14xy^2`
`= x^3 + 2x^2y - (7x^2y + 14xy^2)`
`= x^2(x + 2y) - 7xy(x + 2y)`
`= x(x + 2y)(x - 7y)`
2. `x^4 - 13x^2 + 36`
`= (x^4 - 12x^2 + 36) - x^2`
`= (x^2 - 6)^2 - x^2`
`= (x^2 - 6 - x)(x^2 - 6 + x)`
`= [(x^2 + 2x) - (3x + 6)].[(x^2 - 2x) + (3x - 6)]`
`= [x(x + 2) - 3(x + 2)].[x(x - 2) + 3(x - 2)]`
`= (x - 3)(x + 2)(x + 3)(x - 2)`
3 .`x^2 - 2x - 15`
`= x^2 + 3x - (5x + 15)`
`= x(x + 3) - 5(x + 3)`
`= (x - 5)(x + 3)`
4. `x^2 + 3xy + 2y^2`
`= x^2 + xy + 2xy + 2y^2`
`= x(x + y) + 2y(x + y)`
`= (x + 2y)(x + y)`
Giải thích các bước giải:
