已知x-y=2,x²-y²=6,求x、y的值
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已知x-y=2,x²-y²=6,求x、y的值
已知x-y=2,x²-y²=6,求x、y的值
已知x-y=2,x²-y²=6,求x、y的值
(x+y)(x-y)=6
x-y=2
x+y=3
x=5/2
y=1/2
x+y
=(x²-y²)÷(x-y)
=6÷2
=3
2x=2+3
2x=5
x=2.5
y=2.5-2
y=0.5
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x²-y²=(x+y)(x-y)=6
x+y=3
x=2.5 y=0.5
已知x-y=2 用y表示x即 x=y+2 带入x²-y²=6就会消去y²,结果是y=1/2
x²-y²=(x+y)(x-y)=6,则x+y=3 ,可得x=5/2,y=1/2
x-y=2
x²-y²=6即(x+y)(x-y)=6得x+y=3
则x+y=3
x-y=2
得x=5/2
y=1/2
因为x-y=2, 所以x²-y²=(x-y)(x+y)=6 所以x+y=3 联立x+y=3和x-y=2得到 x=5/2 y=1/2