方程组2x-y=3,3x-4y=3
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1,x+y/2+x-y/3=6即:5x-y=36①4(x+y)-5(x-y)=2即:-x+9y=2②①+②*5==可接2,先化整:3(x+y)+2(x-y)=36①4(x+y)-5(x-y)=2②①*
3(x+y)-4(x-y)=4,①x+y/2+x-y/6=1,则3(x+y)+(x-y)=6②②-①,得5(x-y)=2,解得x-y=2/5③代入②,得x+y=28/15④③+④,得2x=34/15,
5x+y=369y-x=2即45y-10+y=36y=1x=7
合并方程组:x+y/2=3x-2y;3x-2y=10+6x+y/4;得出:x=5y/4;从而算出:x=-25/12,y=-5/3.手机打很累.
3x+4y=104x+3y=-2两式相加7x+7y=87(x+y)=8x+y=8/7
{{x-y)/3-(x+y)/4=2①{(x-y)/6-(x+y)/8=3②②×2得:(x-y)/3-(x+y)/4=6③①与③矛盾∴原方程组无解
(x+y)/2+(x-y)/3=6①5(x+y)-2(x-y)=4②由①得3x+3y+2x-2y=365x+y=36y=36-5x③由②得5x+5y-2x+2y=43x+7y=4④③代入④得3x+25
2(x-y)/3-x+y/4=-1(1)6(x+y)-4(2x-y)=16(2)(1)方程两边同乘以12得8(x-y)-3(x+y)=-12合并同类项得5x-11y+12=0(3)(2)合并同类项得1
化简得:3(x+y)-4(x-y)=43x+3y-4x+4y=4-x+7y=4-x=4-7yx=7y-4(x+y/2)+(x-y/6)=12x+y/3=12(7y-4)+y/3=114y-8+y/3=
先把第二个式子两边同乘以6,则第二个式子就变为3(x+y)+(x-y)=6{1}第二个式子减第一个式子得(x-y)=2{2}x-y=2/5将上式带入{1}中得x+y=28/15{3}由{2}{3}得x
{3x-4y(x-y)=3,2x-3y=12x-3y=1,得x-y=(1+y)/23x-4y(x-y)=3,代入x-y=(1+y)/2,得3x-2y(1+y)=33x-2y-2y²=34y+
x=-11,y=-19|2
4x+3y=1①3x+4y=2②①-②得:x-y=-1.故选A.
3x+2y=k+2①4x+y=4k−1②①-②×2得:-5x=-7k+4,x=7k−45,①×4-②×3得:5y=-8k+11,y=−8k+115,∵关于x,y的方程组3x+2y=k+24x+y=4k
x+y/3=x-y/4⑴2x+3y=11⑵由⑴得x+7y=0,x=-7y(3)将(3)代入⑵得y=-1所以x=7
3x+2y=m+1①4x+y=m②①-②×2得:-5x=-m+1,解得:x=m−15,①×4-②×3得:5y=m+1,解得:y=m+15,即方程组的解是x=m−15y=m+15,∵关于x、y的方程组3
3(x+y)-4(x-y)=43x+3y-4x+4y=4x-7y=-4(1)x+y/2+x-y/6=13x+3y+x-y=62x+y=3(2)(1)+(2)×715x=17所以x=17/15y=3-2
解方程组3x+4y=3x+y=1,得x=1y=0.把x=1,y=0代入2mx+3y=2,得2m+0=2,∴m=1.故答案为1.
(x+y)/2+(x-y)/6=1x/2+x/6+y/2-y/6=12x/3+y/3=12x+y=3(1)3(x+y)-4(x-y)=43x+3y-4x+4y=4-x+7y=4(2)(1)+2*(2)
①-②×3得x=9+6k,代入①得y=-8k+73,代入方程3x+15y=16+2k,得3(9+6k)-15×8k+73=16+2k,解得k=-1.