(x+y)^2=1,x^+xy=3,求2x^2-xy-3y^2的值(x+y)^2=1，x^2+xy=3，求2x^2-xy-3y^2的值

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(x+y)^2=1,x^+xy=3,求2x^2-xy-3y^2的值(x+y)^2=1，x^2+xy=3，求2x^2-xy-3y^2的值(x+y)^2=1,x^+xy=3,求2x^2-xy-3y^2的值

(x+y)^2=1,x^+xy=3,求2x^2-xy-3y^2的值(x+y)^2=1，x^2+xy=3，求2x^2-xy-3y^2的值
(x+y)^2=1,x^+xy=3,求2x^2-xy-3y^2的值
(x+y)^2=1，x^2+xy=3，求2x^2-xy-3y^2的值

(x+y)^2=1,x^+xy=3,求2x^2-xy-3y^2的值(x+y)^2=1，x^2+xy=3，求2x^2-xy-3y^2的值
2x^2-xy-3y^2=(2x-3y)(x+y)=12
x+y=1 x=3 y=-2 2x-3y=12
x+y=-1 x=-3 y=2 2x-3y=-12