因式分解(3道)用“十字相乘法”x^3-5x^2y-24xy^2x^3-3x^2-10x(x^2+4x)^2-x^2-4x-20

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因式分解(3道)用“十字相乘法”x^3-5x^2y-24xy^2x^3-3x^2-10x(x^2+4x)^2-x^2-4x-20
因式分解(3道)
用“十字相乘法”
x^3-5x^2y-24xy^2
x^3-3x^2-10x
(x^2+4x)^2-x^2-4x-20

因式分解(3道)用“十字相乘法”x^3-5x^2y-24xy^2x^3-3x^2-10x(x^2+4x)^2-x^2-4x-20
x^3-5x^2y-24xy^2
=x(x^2-5xy-24y^2)
=x(x-8y)(x+3y)
x^3-3x^2-10x
=x(x^2-3x-10)
=x(x-5)(x+2)
(x^2+4x)^2-x^2-4x-20
=(x^2+4x)^2-(x^2+4x)-20
=(x^2+4x-5)(x^2+4x+4)
=(x+5)(x-1)(x+2)^2

1.=x(x-8y)(x+3y)
2.=x(x-5)(x+2)
3.=(x^2+4x-5)(x^2+4x+4)
=(x+5)(x-1)(x+2)^2