x²-xy-2y²-x+5y-2=?谢谢o(∩_∩)o

x²-xy-2y²-x+5y-2=?谢谢o(∩_∩)o
x²-xy-2y²-x+5y-2=?谢谢o(∩_∩)o

x²-xy-2y²-x+5y-2=?谢谢o(∩_∩)o
=(x-2y)(x+y）-x+5y-2
=(x-2y)(x+y）-2x+x+y+4y-2
=(x-2y)(x+y)+(x+y)-2x+4y-2
=(x+y)(x-2y+1)-2(x-2y+1)
=(x-2y+1)(x+y-2)

将Y看做一个常数，然后利用十字交叉法就可以得到（X-2Y)(4X+3Y)=0
就有:X=2Y,4X=-3Y,所以X/Y=2或X=-3/4
7月w5