Question

2x方+5xy-3y方-3x-16y-5 因式分解

Answer 1

2x^2+5xy－3y^2-3x-16y-5

=(2x-y)(x+3y)-3x-16y-5

=(2x-y)(x+3y)+(2x-y-5)-5x-15y

=(2x-y)(x+3y)-5(x+3y)+(2x-y-5)

=(x+3y)(2x-y-5)+(2x-y-5)

=(2x-y-5)(x+3y+1)

这叫双十字相乘法