1-x^2+4xy-4y^2

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1-x^2+4xy-4y^2
1-x^2+4xy-4y^2

1-x^2+4xy-4y^2
原式=1-(x²-4xy+4y²)
=1-(x-2y)²
=(1+x-2y)(1-x+2y)

3(x-3)+10(2/3+y)=13
22(x-3)+5(2/3+y)=27
令a=x-3,b=2/3+y
则3a+10b=13 (1)
22a+5b=27 (2)
(1)-2*(2)
3a+10b-44a-10b=13-27*2
-41a=-41
a=1,
代入(2)
22+5b=27
b=1
所以...

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3(x-3)+10(2/3+y)=13
22(x-3)+5(2/3+y)=27
令a=x-3,b=2/3+y
则3a+10b=13 (1)
22a+5b=27 (2)
(1)-2*(2)
3a+10b-44a-10b=13-27*2
-41a=-41
a=1,
代入(2)
22+5b=27
b=1
所以x=a+3=4
y=b-2/3=1/3 3(x-3)+10(2/3+y)=13
22(x-3)+5(2/3+y)=27
令a=x-3,b=2/3+y
则3a+10b=13 (1)
22a+5b=27 (2)
(1)-2*(2)
3a+10b-44a-10b=13-27*2
-41a=-41
a=1,
代入(2)
22+5b=27
b=1
所以x=a+3=4
y=b-2/3=1/3

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