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5/x 1 4/y%2

x/y=5/4(x-1)/(y+2)=2/3 y≠0,y≠-2:4x = 5 y3(x-1) = 2(y+2) 4x - 5 y = 0..(1)3x - 2y =7..(2)(1)*2-(2)*5:8x-15x=-35x=5y=4/5x=4

设1/(x+1)=m,1/(y-2)=n原方程组可化为5m-4n=07m-3n=13/20解得m=1/5,n=1/4所以,x+1=5,y-2=4原方程组的解为x=4,y=6

5/(x+1)+4/(y-2)=2 7/(x+1)-3/(y-2)=13/20 设1/(x+1)=a,1/(y-2)=b 5a+4b=2, 15a+12b=6 7a-3b=13/20,28a-12b=13/5 43a=43/5, a=1/5, x+1=5,x=4 b=(2-5a)/4=1/4, y-2=4,y=6

把第一个X20 得4X+5Y=46 ③把第二个X21 得7Y-3X=30 ④把③X3+④X4 得43X=258 X=6把X=2代入③ 得8+5Y=46 5Y=38 Y=7.6应该对吧 - -望采纳

5/(x+1)+4/(y+2)=2 7/(x+1)+ 3/(2-3) =13/20 3/(2-3)???错了吧

由(1)得x=5y/4 (3)由(2)得3x-3=2y+43x-2y=7 (4)把(3)代入(4)得15y/4-2y=715y-8y=28∴y=4把y=4代入(3)得x=5∴x=5 y=4

5/12X-X/4=1/3解:1/6*X=1/3 X=1/3÷1/6 X=21/2*Y-1=1/5*Y+2解:1/2*Y-1/5*Y=2+1 3/10*Y=3 Y=3÷3/10 Y=10

依题,y=5/x+1 y^2=2x+1/4 y的一次方 y的二次方互为相反数即 y=-y^2时 -5/x-1=2x+1/42x^2+1/4x+5+x=0 8x^2+5x+20=0 根据韦达定理 b^2-4ac<0 x无解 因此无论x为何值y的一次方 y的二次方互为相反数都不能实现

(1)5(x-y)+2(x-y)-4(x-y).=(5+2-4)(x-y)=3(x-y)(2)3(x-y)-4(x-y)+7(x-y)-6(x-y).=(3-6)(x-y)+(7-4)(x-y)=-3(x-y)+3(x-y)

由x/y=5/4 得 x=5y/4---(1) x-1/y+2 得x=2y+7/3---(2) (1)=(2)得 y=4,代入(1)或(2)得 x=5 当x=5,y=4时满足原方程组有意义所以 x=5,y=4 . 呵呵 好好学习哦!

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