91 x=3(49 y)-12x=86
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![91 x=3(49 y)-12x=86](/uploads/image/f/413479-55-9.jpg?t=91+x%3D3%2849+y%29-12x%3D86)
x=3yx+y=12所以x=9,y=3x-y=9-3=6
这是一个问题还是分开的啊?再问:feikai再答:/代表几分之几,*代表乘号1.3x+8y=12①14x+5y=12②②-①=11x-3y=011x=3y11/3*x=y再代入①里计得x,再代入②再问
解析:令x+y=m,x-y=n,那么原方程组可化为:{2分之m+3分之n=6(1){2m+n=12(2)(1)×6可得:3m+2n=36(3)(2)×2可得:4m+2n=24(4)(4)-(3)可得:
令a=x²+y²则a²-a=12a²-a-12=0(a-4)(a+3)=0a=4,a=-3平方数大于等于0所以a=-3不成立所以x²+y²=
2x-y/x+3y=2得x+3y/2x-y=1/24x-2y/x+3y减4x+12y除以2x-y=2(2x-y)/x+3y-4(x+3y)/2x-y=2乘以2-4乖以1/2=4-2=2
x+y+z-6=02x+3y-z-12=02x-y-z=0组成方程组再解x=2y=3z=1
答案是2.4x-2y/x+3y=(2x-y/x+3y)乘以2=4,4x+12y/2x-y=(x+3y/2x-y)乘以4=1/2x4=2,所以代数式等于4-2=2.
原式=x2+4xy+4y2-2(x2-y2)+2xy-6y2=x2+4xy+4y2-2x2+2y2+2xy-6y2=-x2+6xy,当x=-2,y=12时,原式=-(-2)2+6×(-2)×12=-4
x=3y3y+y=12y=3x=9x-y=6
X+Y分之X-Y等于3x=-2yX+Y分之2(x-y)减X+Y分之3X+Y=(-x-3y)/(x+y)=1
.死算呗xy-2x+3y-6=xy+10x-3y-30,2x-y=4xy+3x+y+3=xy+12x-2y-24,3x-y=92式减1式,x=5,y=6
因为(x-y)/(x+y)=3,则(x+y)/(x-y)=1/3则5(x-y)(x+y)-(x+y)/2(x-y)=5*3-1/(3*2)=15-1/6=89/6
(3x/24+2x/24)*3+(2x/24+x/24)y=x15x/24+3xy/24=x15x+3xy=24x9x-3xy=03x-xy=0x(3-y)=0结果:x=0或y=3
不妨方程x-2y=-9标注为(1),方程3x-y+z=4标注为(2),方程y-z=3标注为(3),则有(2)-(1)*3=(3x-y+z)-(x-2y)*3=4-(-9)x3,即为5y+z=31,标注
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
解(x-y)(x+y)-(x-2y)²+x(3x-5y)-(x-y)(x-2y)=(x²-y²)-(x²-4xy+4y²)+(3x²-5xy
#includesintjiesheng(intn)//用于计算阶乘如:3!{if(n=1)rerunn;returnn*hh(n-1)}doubledigui(intn,intx)//用以计算y=x
x^2=12x=±2√3y^2=3y=±√3|x-y|=y-x说明y-x≥0即y≥x所以x不可能等于2√3,即x=-2√3若y=-√3,x+y=-3√3若y=√3,x+y=-√3
3y=2x,两边同时乘以1/3x可得y/x=2/3;y/3=x/2,两边同时乘以3/x可得y/x=3/2;12/x=9y,两边都乘以x/9可得x/y=4/3.