十字相乘法

48^2+2-1
=2305
16^2+40y+25
=281+40y
-13+x^2+12x
=x^2+12x-13
=(x+13)(x-1)
4+3x-x^2
=-(x^2-3x-4)
=-(x+1)(x-4)
a^2+63+16a
=a^+16a+63
=(a+6)(a+7)
2x+48-x^2
=-(x^2-2x-48)
=-(x+6)(x-8)
(m-2)(m-3)-12
=m^2-3m-2m+6-12
=m^2-5m-6
=(m+1)(m-6)
16+(m-3)(m+7)
=16+m^2+7m-3m-21
=m^2+4m-5
=(m-1)(m+5)
I'm sorry that I don't know about this x^2-xy+12y^2 , 2X^2x-y^2 , 15x^2-14xy-8y^2

樓上的朋友,我幫你吧 x^2-xy+12y^2 , 2X^2x-y^2 , 15x^2-14xy-8y^2
x^2-xy+12y^2
=無解(也可以說無實數解)

2X^2x-y^2(你個有大同小Xx係點解呢)

15x^2-14xy-8y^2
=(5x+2y)(3x-4y)