解方程组2x y=2,2x y=5
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![解方程组2x y=2,2x y=5](/uploads/image/f/7208921-65-1.jpg?t=%E8%A7%A3%E6%96%B9%E7%A8%8B%E7%BB%842x+y%3D2%2C2x+y%3D5)
这个不是很难的:首先,根据第一个方程,x^2-2xy+y^2=(x-y)^2=1得到:x-y=1或者x-y=-1然后,分两种情况计算(1)x=y+1代入第二个方程,2x^2-5xy-3y^2=0可以得
第一题设x+y=axy=b则x^2+y^2=a^2-2b原方程变为a^2-2b+b=13①b+a=7②这就变成了简单的二元二次方程由②得b=7-a带入①得a^2+a-20=0(a-4)(a+5)=0得
xy/(2x+y)-xy/(2x-y)=3xy/(2x-y)+xy/(2x+y)=4;一、两公式对加得2xy/(2x+y)=7xy=(2x+y)*7/2二、把xy代入原公式求解就行了:(2x+y)*7
X²-XY+2X=O提公因数X即X(X-Y+2)=0则X=0或X-Y+2=0假如X=0那么代入X²-2XY+Y+8=0解得Y=﹣8即X=0Y=﹣8假如X≠0则X-Y+2=0即X=Y
∵2xy-5√(xy+1)=10==>2xy+2-5√(xy+1)=12==>2(xy+1)-5√(xy+1)-12=0==>[2√(xy+1)+3][√(xy+1)-4]=0(用十字相乘法分解)==
消掉y得2x(x-1)=2即x(x-1)=1,所以,x=(1+根号5)/2,对应y=(根号5-1)/2或x=(1-根号5)/2,对应y=(-根号5-1)/2这里用了求根公式!得解!
解1式:(x+4y)(x-y)=0x=-4y时,解2式得:x=-10/3,y=5/6;x=10/3,y=-5/6x=y时,解2式得:x=5,y=5;x=-5,y=-5
x²-2xy+y²=12x²-5xy-3y²=0即(x-y)²=1(2x+y)(x-3y)=02x+y=0或x-3y=0如果2x+y=0,则y=-2x
x^2+xy+2y^2=9+y2x^2+2xy+4y^2=18+2y2x^2+2xy+4y^2+x=1918+2y+x=19x+2y=1x=1-2y(1-2y)^2+(1-2y)y+2y^2-y=94
xy/3x+2y=1/8,xy/2x+3y=1/73x+2y/xy=8,2x+3y/xy=73/y+2/x=8,2/y+3/x=73/y+2/x=8,2/y+3/x=71/x=1,1/y=2,x=1,
两式相减x²-10x-y²+10y=0x²-y²-10(x-y)=0(x+y)(x-y)-10(x-y)=0(x+y-10)(x-y)=0x+y=10x-y=0
2x²+5xy-2y²=5(1)3x²-xy+6y²=8(2)(1)*8-(2)*5x²+45xy-46y²=0(x-y)(x+46y)=0
2x=xy+3(2-y)x=3x=3/(2-y)当y=-1,0,1,时x=1,1/2,3所以有两组(-1,1),(1,3)
x+y=-3x=-3-y带入xy=2(-3-y)y=2-y^2-3y-2=0y^2+3y+2=0(y+1)(y+2)=0y1=-1y2=-2x1=-2x2=-1
x=2,y=0.5
x²+2xy+y²=4x²-xy-y²=0方程1化为(x+y)²=4,得x+y=2或x+y=-2将x=2-y代入方程2得:4-4y+y²-2
由(x-2)(y+3)=xy(x-5)(y+2)=xy得3x-2y-6=02x-5y-10=0上面方程化为6x-4y-12=06x-15y-30=0两式相减得11y=-18,y=-18/11,代入任意
x=oy=o再问:错了再答:哪里错?再答:验证符合哎再问:x+y=xz,x+2y=xz²再问:x,y≠0再答:你都给的错题再问:呵呵再答:算我对啦😜再问:额
x^2-xy+y^2=3,2x^2-xy-y^2=55x^2-5xy+5y^2=156x^2-3xy-3y^2=15两式子相减x^2+2xy-8y^2=0(x+4y)(x-2y)=0x=2y或者x=-