2X-3Y=8 { 5X-7Y=5

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2X-3Y=8{5X-7Y=52X-3Y=8{5X-7Y=52X-3Y=8{5X-7Y=5由1.得x=(8+3y)/2,将x=(8+3y)/2带入2.得(40+y)/2=5,y=-30,x=-412X

2X-3Y=8 { 5X-7Y=5
2X-3Y=8 { 5X-7Y=5

2X-3Y=8 { 5X-7Y=5
由1.得x=(8+3y)/2,将x=(8+3y)/2带入2.得(40+y)/2=5,y=-30,x=-41

2X-3Y=8 .......(1)
5X-7Y=5......(2)
(1)*5-(2)*2得
-y=30
y=-30
代入(1)得
2x+90=8
x=-82
x=-41
解得
x=-41
y=-30

2x-3y=8①，5x-7y=5② ①×5-②×2，得-y=30，即y=-30，将y=-30带入①，得2x+90=8，解得x=-41∴x=-41，y=-30

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