1.6y^2-11y-102.5x^5-15x^3y-20xy^2
问题描述：
1.6y^2-11y-10
2.5x^5-15x^3y-20xy^2
答
1. 6y^2-11y-10
＝（3Y+2）(2Y-5)
2. 5x^5-15x^3y-20xy^2=5X(X^2-4Y)(X^2+Y)
答
1. 6y^2-11y-10
=(2y-5)(3y+2)
2. 5x^5-15x^3y-20xy^2
=5x(x^4-3x^2y-4y^2)
=5x(x^2-4y)(x^2+y)
答
十字相乘法：
1. 6y^2-11y-10
2y -5
3y +2
-------
-15y+4y = -11y
所以 6y^2-11y-10 = (2y-5) (3y-2）.
2. 5x^5-15x^3y-20xy^2
= x(5x^4-15x^2y-20y^2)
5x^2 +5y
x^2 -4y
----------
5x^2y -20x^2y = -15x^2y
所以 5x^5-15x^3y-20xy^2 = x(5x^2+5y)(x^2-4y).
答
1.(3y-2)(2y-5)
答
6y^2-11y-10
=(2y-5)(3y+2)
5x^5-15x^3y-20xy^2
=5x(x^4-3x^2y-4y^2)
=5x(x^2+y)(x^2-4y)