方程组5x--y=36,-x--9y=2
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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*
3x+4y=14——①5x-6y=36——②∴①*5-②*3得:38y=-38解得:y=-1代入①式得:x=6∴x=6y=-1
40x=2x25y40x=50yy=5/4xx+y=36x+5/4x=369/4x=36x=16y=16x5/4=202x+3y=15.54x+6y=315x+6y-4x-6y=35-31x=42x4
5x+3y=361-x+9y=22将1x5得:-5x+45y=103将3+1得48y=46y=24分之23将y=24分之23代入1等于5x+24分之69=36x=
5x+y=369y-x=2即45y-10+y=36y=1x=7
3x+3y+2x-2y=36①4x+4y-5x+5y=2②(3x+2x)+(3y-2y)=365x+y=36y=36-5x③把③带入②得,-x+9(36-5x)=2x=7把x=7带入③得y=1∴此方程
补充题目:已知方程组5x+y=3;ax+5y=4与方程组x-2y=5,5x+by=4有相同的解,求a,b的值.解答;说明,最后相同的解是四个方程的解也为方程组5x+y=3,x-2y=5的解此方程组的解
5(x+y)+3(x-y)=908x+2y=901式5(x+y)-3(x-y)=302x+8y=302式1式乘以4-2式解得x=11y=1
5x+3y=36,(1)-x+9y=2(2)(1)*3-(2)3*5x+x=36*3-216x=106x=53/8y=(2+53/8)/9=23/24
x=66/37y=-28/37
3x=4(x-y)化简得x-y=0…………①x-8(x-y)=58y-7x=5…………②①×7+②得15x=5x=3分之1把x=3分之1代入①得3分之1-y=0y=3分之1∴x=3分之1,y=3分之1
-x+9y=2,x=9y-2代入5x+3y=36:5(9y-2)+3y=3648y=46y=23/24x=9*23/24-2=159/24
令x/4=y/5=K,则x=4k,y=5k.所以12k-10k=10.解得K=5.则x=4k=20,y=5k=25.所以x=20,y=25
x=-11,y=-19|2
化简成:45x+9y=324-x+9y=2两式相减:x=7y=1
x+y=a(1)(a-1)x+y=5(2)(2)-(1)(a-1-1)x=5-ax=(5-a)/(a-2)y=a-x=a-(5-a)/(a-2)=(a²-a-5)/(a-2)
展开x^2-2y^2-xy=-5x^2-2y^2+xy=7所以x^2-2y^2=1xy=6上式除以下式,解分式方程x/y=3/2或-4/3(舍去)所以x^2=9y^2=4x=3y=2或x=-3y=-2
设1/x+y=t1/x-y=v则3t+2v=17/52t-5v=16t+4v=34/56t-15v=319v=19/5v=1/5t=11/x+y=11/x-y=1/5x+y=1x-y=5x=3y=-2
3x+5(x+y)=36①3y+4(x+y)=0②①+②:12(x+y)=36,x+y=3带入原式可得3x+15=36,x=73y+12=0,y=-4