{3分之x-4分之y＝1-搜答案-神马作文网

1/3x+3/4y=5/12.(1)2/3x-5/6y=-1/3.(2)去分母：4x+3y=4.(3)4x-5y=-2.(4)(3)-(4)得：8y=6y=3/44x+3*3/4=44x=7/4x=7

=(2X/3Y)*(3X/4Y)*(4/xy)=(2x*3x*4)/(3y*4y*xy)=2x/(y^3)

(2X)/3＋(3Y)/4＝1/5(5X)/6-(5Y)/2＝2(2X)*4＋(3Y)*3＝12/5(5X)-(5Y)*3＝1240*X＋45*Y＝125*X-15*Y＝1215*X-45*Y＝365

x=5,y=8再问：过程打一下再答：(x+15)(y-6)=(x-1)(y+2)xy-6x+15y-90=xy+2x-y-216y=8x+882y=x+114x-xy=x-3-xy+3y3x=-3+3

再问：用代入法

3）把①式乘以10,②式乘以6,得：25x+2y=-402x+y=1由下式得y=1-2x,代入上式得25x+2-4x=-4021x=-42x=-2则y=1+4=54）把①式乘以6,②式乘以2得3x-y

②*2-①得,5/y+11=0∴y=-5/11代入②得,1/x-44/5+6=0∴x=5/14经检验,符合题意∴方程组的解是：x=5/14y=-5/11

X/3+Y/4=1得4X+3Y=12(两边乘12)Y/3-X/2=1得2Y-3X=6(两边乘6)一式-二式得Y+7X=6Y=6-7X代入二式12-14X-3X=6X=6/17Y=60/17再问：对不起

3x/4+2y=(2x+y)/5=(x-y+1)/6则3x/4+2y=(2x+y)/5―→15x+40y=8x+4y→7x+36y=0――①(2x+y)/5=(x-y+1)/6―→12x+6y再问：麻

第一个两边乘128(x-y)-3(x+y)=-128x-8y-3x-3y=-125x-11y=-12(1)第二个6x+6y-8x+4y=16-2x+10y=16x-5y=-8(2)(1)-(2)×55

2x/3+3y/4=7/12(1)x/6-y/2=-1/3(2)(1)*12(2)*68x+9y=7(3)x-3y=-2(4)(4)*33x-9y=-6(5)（3）+（5）11x=1x=1/11将x=

=3x/(x-4y)-(x+y)/(x-4y)-7y/(x-4y)=(3x-x-y-7y)/(x-4y)=(2x-8y)/(x-4y)=2(x-4y)/(x-4y)=2

因为：3分之x+1=4分之y+3=5分之x+y,所以：（x+1）/3=（y+3）/4=(x+y)/54x+4=3y+94x=3y+55x+5=3x+3y2x=3y-5x=5y=5则x+2y+3分之3x

3/x-5/y=5……①3/2x+5/y=5/4……①+②得x=18/25将x代入①式,得y=-6

x-4y分之3x+4y-x分之x+y-x-4y分之7y=3x/(x-4y)-(x+y)/(x-4y)-7y/(x-4y)=(3x-x-y-7y)/(x-4y)=(2x-8y)/(x-4y)=2

x分之4+y分之3=10x分之9-y分之7=-54/x-3/y=10①9/x-7/y=-5②①*123x-4y=120③②*637x-9y=-315④③*36108x-144y=120⑤④*428x-

原式等价于10(x+1)=5(y+3)=4(x+y)10(x+1)=5(y+3)可得2x-y=15(y+3)=4(x+y)可得4x-y=15解得x=7y=13x+2y+3=363x+2y+1=48两式