x+y等于1,2x+y等于3,解是多少
\u82e5x^2+x-2=3 \u52192x^2+2x+1\u7b49\u4e8e\u60a8\u597d\uff1a
2x^2+2x+1
=2x^2+2x-4+5
=2(x^2+x-2)+5
=2x3+5
=6+5
=11
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[x(3-4x)+2x^2(x-1)]/(-2x)=[3x-4x^2+2x^3-2x^2]/(-2x)
=(2x^3-6x^2+3x)/(-2x)=-x^2+3x-3/2
2x + y = 3 ②
② - ① 得:
x = 2
把 x = 2 代入 ① 得:
y = -1
综上:
x = 2
y = -1
x=2.y=-1
x+(x+y)=3
x=2
y=-1
X=2 Y= -1
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