已知x减y=2,x的平方减y的平方=12
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把25拆成16+9(x²-8x+16)+(y²+6y+9)=0(x-4)²+(y+3)²=0平方大于等于0,相加等于0若有一个大于0,则另一个小于0,不成立.所
x^2+y^2=6y-4x-13x^2+4x+4+y^2-6y+9=0(x+2)^2+(y-3)^2=0x=-2y=3x^2-y^2=(-2)^2-3^2=4-9=-5
答:x²+y²-2x+8y+17=0(x²-2x+1)+(y²+8y+16)=0(x-1)²+(y+4)²=0所以:x-1=0y+4=0解得
[(x的平方+y的平方)-(x-y)的平方+2y(x-y)]/4y=(x^2+y^2-x^2+2xy-y^2+2xy-2y^2)/4y=(2x-y)/2=4022/2=2011
x-3y=0x=3y原式=(2x+y)(x-y)/(x-y)²=(2x+y)/(x-y)=(6y+y)/(3y-y)=7y/2y=7/2
已知x=二分之一,xy(y加y的二次方)减y的二次方(xy-x)+2x(x-y的平方)的值=xy²+xy³-xy³+xy²+2x²-2xy²
x=-3y=4式子等于-49/12
两式子相加相减得(X+Y)的平方=16X方-Y方=12题一解为4题二解为4
x²-4x-1=0x²-4x=1所以:(2x-3)²-(x+y)(x-y)-y²=4x²-12x+9-(x²-y²)-y²
x平方+xy-2y的平方=0,(x-y)(x+2y)=0x-y=0或x+2y=0x=y或x=-2yx/y-y/x-x的平方+y的平方/xy=(x²-y²-x²-y
{(x的平方+y的平方)-(x的平方-y的平方)+2y(x-y)}除4y=(2y^2+2y(x-y)/(4y)=2xy/(4y)=x/2
(x+y)(x-y)-y^2+(x-y)^2-(6x^2y-2xy^2)/(2y)=X^2-y^2-y^2+X^2+y^2-2xy-3x^2+xy=-x^2-y^2-xy=-(x^2+y^2+xy-3
x-y=(x²-y²)/(x+y)=15/5=3;
x^2-y^2=(x+y)(x-y)=3(x-y)=9x-y=3
x-y=(x+y)(x-y)=13因为x+y=5所以x-y=13/5
原方程化为(x+1)^2-(y-3)^2=0化简得|x+1|=|y-3|由于x+y≠2,所以x+1=y-3故x-y=-4
先由两已知方程解得x=27/8,y=9/8,然后接下来的自己算啦...两方程的话,先将第二个两边都乘三,再于第一个相减得出y,再将y带进方程得x
x的平方+y的平方-2x+4y=-5x²-2x+1+y²+4y+4=0﹙x-1﹚²+﹙y+2﹚²=0x-1=0,y+2=0x=1,y=-2
x=1,y=-1