Đáp án `+` Giải thích các bước giải `!`
`a)`
`(x^4+2x^3+10x-25) : (x^2+5)`
`= (x^4+2x^3-5x^2+5x^2+10x-25) : (x^2+5)`
`= [(x^4+2x^3-5x^2)+(5x^2+10x-25)] : (x^2+5)`
`= [x^2(x^2+2x-5)+5(x^2+2x-5)] : (x^2+5)`
`= [(x^2+5)(x^2+2x-5)] : (x^2+5)`
`= x^2+2x-5`
`b)`
`(x^3-3x^2+5x-6) : (x-2)`
`= (x^3-x^2+3x-2x^2+2x-6) : (x-2)`
`= [(x^3-x^2+3x)-(2x^2-2x+6)] : (x-2)`
`= [x(x^2-x+3)-2(x^2-x+3)] : (x-2)`
`= [(x-2)(x^2-x+3)] : (x-2)`
`= x^2-x+3`
`c)`
`-5xy(3x^2y-5xy+y^2)`
`= -(5xy. 3x^2y)+(5xy. 5xy)-(5xy. y^2)`
`= -15x^3y^2+25x^2y^2-5xy^3`
Áp dụng: `a(b+c) = ab+ac`
