Question

分解因式x^2-10x-11 x^2y^2-16xy+60 (x+y)^2-7(x+y)-18 x^2-13xy-30y

Answer 1

x^2-10x-11 =(x-10)(x+1)

x^2y^2-16xy+60 =(xy-10)(xy-6)

(x+y)^2-7(x+y)-18 =(x+y-9)(x+y+2)

x^2-13xy-30y^2 =(x-15y)(x+2y)

(a+b)^2+9(a+b)-22 =(a+b+11)(a+b-2)

都可以用十字相乘分解