已知|x-1/x-9 - y-1/y+15|+|x+6/x+9 - y-3/y|=0 求12y2-490/x
来源:学生作业帮 编辑:搜搜考试网作业帮 分类:数学作业 时间:2024/08/05 16:06:14
已知|x-1/x-9 - y-1/y+15|+|x+6/x+9 - y-3/y|=0 求12y2-490/x
![已知|x-1/x-9 - y-1/y+15|+|x+6/x+9 - y-3/y|=0 求12y2-490/x](/uploads/image/z/17833566-30-6.jpg?t=%E5%B7%B2%E7%9F%A5%7Cx-1%2Fx-9+-+y-1%2Fy%2B15%7C%2B%7Cx%2B6%2Fx%2B9+-+y-3%2Fy%7C%3D0+%E6%B1%8212y2-490%2Fx)
绝对值都是非负的
所以( x-1/x-9) - (y-1)/(y+15)=0且 (x+6)/(x+9) - (y-3)/y=0
所以 (x-1)(y+15)=(x-9)(y-1) 且 (x+6)y=(x+9)(y-3)
所以 xy-y+15x-15=xy-x-9y+9且xy+6y=xy-3x+9y-27
所以 16x+8y=24且 3x-3y=-27
即 2x+y=3且 x-y=-9
所以 x=-2,y=7
(12y²-490)/x
=(12*49-49*10)/(-2)
=2*49/(-2)
=-49
所以( x-1/x-9) - (y-1)/(y+15)=0且 (x+6)/(x+9) - (y-3)/y=0
所以 (x-1)(y+15)=(x-9)(y-1) 且 (x+6)y=(x+9)(y-3)
所以 xy-y+15x-15=xy-x-9y+9且xy+6y=xy-3x+9y-27
所以 16x+8y=24且 3x-3y=-27
即 2x+y=3且 x-y=-9
所以 x=-2,y=7
(12y²-490)/x
=(12*49-49*10)/(-2)
=2*49/(-2)
=-49
已知4x=9y求(1)x+y/y (2)y-x/2x
已知实数x,y满足x2+3y2+6x-12y+21=0,求x,y的值
已知x2-4x-1=0,求代数式(2x-3)2-(x+y)(x-y)-y2的值
已知y=y1+y2,y与x+1成正比例,y2与x成反比,当x=1时,y=0,当x=4时,y=9,求y与x的函数关系
已知x>0 y>0 1/x+9/y=1 求x+y最小值
{4/(x+y)+6/(x-y)=3 {9/(x-y)-1/(x+y)=1
已知实数x,y满足(x2)+(y2)-xy+2x-y+1=0,求x,y的值
已知实数x、y满足X2+y2-xy+2x-y+1=0,试求x、y的值
已知x2+y2-10x-6y+34=0,求y\x+y的值
已知X.x+y.y-4x+2y+5=0,求4X.X-12X Y+9Y.y的值
已知[(x2+y2)-(x-y)2+2y(x-y)]÷4y=1,求4x/4x2-4y2-1/2x+y的值,
已知Y=Y1+Y2,Y1与X成正比例,Y2与X平方成反比例,且x=2时y=0,当x=-1时y=9/2,求y与x之间的函数