已知x平方-4y平方=20,x 2y=5,求x,y的值
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3x^2+xy-2y^2=(3x-2y)(x+y)=0x=-2y/3,或x=-y但由于你要求的式子中分母里有X平方-Y平方x=-y舍去其他就代入吧
十分简单x^2-2xy+y^2+y^2-4y+4=0(x-y)^2+(y-2)^2=0x=y=2x^2+y^2=8
x²+4y²-2x+4y+2=0(x-1)²+(2y+1)²=0∴x=1,y=-1/2∴x四次方-y四次方/2x平方+xy-y平方*2x-y/xy-y平方/(x
4x^2-3y^2=73x^2+2y^2=19相加7x^2-y^2=26所以14x^2-2y^2=2(7x^2-y^2)=2*26=52
x^2+y^2-4x+6y+13=0x^2-4x+4+y^2+6y+9=0(x-2)^2+(y+3)^2=0x-2=0,y+3=0x=2,y=-3(x^2+y)/(x^2-y)=(4-3)/(4+3)
x^2+y^2-4x-6y+13=0(x^2-4x+4)+(x^2-6y+9)=0(x-2)^2+(y-3)^2=0所以(x-2)^2=0,(y-3)^2=0x-2=0,y-3=0x=2,y=3xy/
(x平方+y平方)平方-y平方=x平方+6所以(x²+y²)²-(x²+y²)-6=0(x²+y²+2)(x²+y
已知5x-4y=0,切xy≠0,x/y=4/5;求(x平方-y平方)分之(x平方+y平方)-(x-y)分之(x+y)的值=(x²+y²)/(x²-y²)-(x+
x的平方-4y的平方=20,==>X^2-4Y^2=20==>(X+2Y)(X-2Y)=20x+2y=5,(1)==>X-2Y=4(2)(1)+(2).2X=9==>X=9/2(1)-(2).4Y=1
因为x²+y²-4x+2y+5=0所以(x²-4x+4)+(y²+2y+1)=0所以(x-2)²+(y+1)²=o所以x=2y=-1所以下面
x的平方-4x+y的平方-6y+13=x的平方-4x+4+y的平方-6y+9=(x-2)的平方+(y-3)的平方=0由于(x-2)的平方和(y-3)的平方都≥0,因此x-2=0,y-3=0,x=2,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+2)²+(y-1)²=9∴设x=3sina-2y=3cosa+1∴x²+y²=-4x+2y+4=-12sina+8+6cosa-2=-12sina+6co
x/y+y/x=2,(x^2+y^2)/xy=2,所以x^2+y^2=2xy原式=3xy/(-2xy)=-3/2
x平方-y平方=4(x+y)(x-y)=4(x+y)平方*(x-y)平方=4*4=16
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-y)^2=x^2+y^2-2xy=12xy=x^2+y^2-1=4-1=3(x+y)^2=x^2+y^2+2xy=4+3=7x^2y^2=(xy)^2=(3/2)^2=9/4
x+y=7x-y=4解得,x=11/2,y=3/2或x+y=-7x-y=4解得,x=-3/2,y=11/2所以x²+y²=65/2再问:x+y=7怎么来的?请教一下谢谢再答:(x+
A=4X^2-4XY+Y^2,.(1)B=X^2+XY-5Y^2.(2).(2)*4+,.(1)A+4B=8X^2-19Y^28X^2-19Y^2=A+4B4X^2-3XY=1,X^2-4Y^2=-3
A=4x²-4xy+y²,B=x²+xy-5y²A+3B=(4x²-4xy+y²)+3(x²+xy-5y²)=4x