二元二次方程组的解法(一道题)


x2+xy-12=0
xy-2y2-1-0

解:①-②*12得:X2-11XY+24Y2=0
(X-3Y)*(X-8Y)=0
X=3Y 或X=8Y
把X=3Y代入① Y=1或Y=-1
∴X=3 X=-3
把X=8Y代入① Y=(根号6)/6 或Y=-(根号6)/6
∴X=(4倍根号6)/3 X=-(4倍根号6)/3

∴X=3 X=-3 X=(4倍根号6)/3 X=-(4倍根号6)/顶供侈佳侬簧畴伪川镰3
∴Y=1 Y=-1 Y=(根号6)/6 Y=-(根号6)/6


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