解方程组3x加2y=39,4x-3y=18
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4x-3y=7①(x-1)/3=(2y+3)/4②②两边乘以12,得4(x-1)=3(2y+3)4x-6y=13③①-③,得3y=-6y=-2代入①中,得x=1/4x=1/4y=-2
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,
3x+2y=2m+5(1)2x-y=4(2)x+y=5(3)由题意,满足(2)(3)同样满足(1)(2)+(3)3x=9x=3,y=2代入(1)3*3+2*2=2m+513=2m+5m=4
5x+y=369y-x=2即45y-10+y=36y=1x=7
2分之2x+y加3分之2x-y=1,——》10x+y=6,.(1)4*(2x+y)-5(2x-y)=8,——》9y-2x=8,.(2)(1)+(2)*5,得:46y=46,即y=1,代入(1),得:x
原方程组变形得:①3﹙x+y﹚-﹙x-y﹚=4②3﹙x+y﹚+﹙x-y﹚=6∴①+②得:③x+y=10/3②-①得:④x-y=1∴③+④得:x=13/6③-④得:y=7/6∴x=13/6,y=7/6.
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.
{{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
设a=x+y,b=x-y原方程组为:a/2+b/3=6,即3a+2b=36,即:12a+8b=1444a-5b=12,即:12a-15b=36相减得:23b=108,得:b=108/23,再得:a=1
方程化为-x+7y=1117x+3y=272将1式化为x=7y-113则将3式代入2式可得7(7y-11)+3y=2752y=104y=2x=7×2-11x=3所以解得x=3y=2
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=
先将第一个等式整理得12X+Y=36,第二个等式整理得-X+9Y=2,由第一个等式得Y=36-12X,通过换元法得-X+9(36-12X)=2,解出X=322/109,再把X=322/109代入-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+
这慢慢做不就好了,这么简单的式子
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
化简得:-x+7y=11①7x+3y=27②①式×7得:-7x+49y=77③②+③得:52y=104∴y=2代入①得:x=3∴x=3,y=2
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
(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)