若圆C:x^2+y^2+2x-4y+3=0关于直线2ax+by+6=0对称,则由点M(a,b)向圆所作的切线长的最小值是?
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若圆C:x^2+y^2+2x-4y+3=0关于直线2ax+by+6=0对称,则由点M(a,b)向圆所作的切线长的最小值是?若圆C:x^2+y^2+2x-4y+3=0关于直线2ax+by+6=0对称,则
若圆C:x^2+y^2+2x-4y+3=0关于直线2ax+by+6=0对称,则由点M(a,b)向圆所作的切线长的最小值是?
若圆C:x^2+y^2+2x-4y+3=0关于直线2ax+by+6=0对称,则由点M(a,b)向圆所作的切线长的最小值是?
若圆C:x^2+y^2+2x-4y+3=0关于直线2ax+by+6=0对称,则由点M(a,b)向圆所作的切线长的最小值是?
若圆C关于直线2ax+by+6=0对称,
那么圆心(-1,2)在直线上,
带入直线得到
a-b=3.
圆心为C,圆的半径r^2=2
M(a,b)向圆所作的切线长L^2=MC^2-r^2=(a+1)^2+(b-2)^2-2
把a=b+3
带入得到L^2=2b^2+4b+18=2(b+1)^2+16>=16
所以切线长的最小值为4
(x-y) (x-2y)+(x+2y) (x-3y)-2(x-3y) (x-4y)=
如果A={(x,y)|x,y+2>0},B={(x,y)|2x+3y-6>0},C={(x,y)|x-4
x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2
3(x+y)+2(x-y)=36 4(x+y)-5(x-y)=2
(x+y)/2- x-y/2=6 3(x+y)=4(x-y)
x+y/3+x-y/2=6 4(x+y)-2(x-y)=40
2(x+y)-3(x-y)=3 ,4(x+y)+3(x-y)=15
{3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1
x+y/2+x-y/3=6,4(x+y)-3(x-y)=-20
{(x+y)/2+(x-y)/3=6 4(x+y)-3(x-y)=-20
4(x+y)-3(x-y)=-20,2/x+y+3/x-y=6
3(x+y)-2(x-y)=11 4(x+y)+3(x-y)=9
4(x-y)-3(x-y)=9 5(x-y)+2(x-y)=11
3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27
先化简再求值(x-y)(x-2y)+(x-2y)(x-3y)-2(x-3y)(x-4y) x=4 y=5
已知2y-x=-3,求[4y(2x-y)-2x(2x-y)]/(2x-y
x+y+2(-x-y+1)=3(1-y-x)-4-(y+x-1),x+y=?
设A={(x,y)}|3x+2y|.设A={(x,y)}|3x+2y|.B={(x,y)|x-y=2|},C={(x,y)|2x-2y|=3},D={(x,y)|6x+4y=2|},求A∩B,B∩C,A∩D设A={(x,y)|3x+2y=1}.B={(x,y)|x-y=2},C={(x,y)|2x-2y=3},D={(x,y)|6x+4y=2},求A∩B,B∩C,A∩D