已知直线l：y=kx+b与椭圆C：3x^2+y^2=3相交于A、B两点,M是的线段AB的中点,O是坐标原点 (1)当l与直线x+y=0平行(不重合)时,求直线OM的斜率(2)如果|OM|=1,证明b^2=((k^2)+3)^2/((k^2)+9),并求线段AD长取最大值时

已知直线l：y=kx+b与椭圆C：3x^2+y^2=3相交于A、B两点,M是的线段AB的中点,O是坐标原点 (1)当l与直线x+y=0平行(不重合)时,求直线OM的斜率(2)如果|OM|=1,证明b^2=((k^2)+3)^2/((k^2)+9),并求线段AD长取最大值时
已知直线l：y=kx+b与椭圆C：3x^2+y^2=3相交于A、B两点,M是的线段AB的中点,O是坐标原点
(1)当l与直线x+y=0平行(不重合)时,求直线OM的斜率
(2)如果|OM|=1,证明b^2=((k^2)+3)^2/((k^2)+9),并求线段AD长取最大值时直线l的方程

已知直线l：y=kx+b与椭圆C：3x^2+y^2=3相交于A、B两点,M是的线段AB的中点,O是坐标原点 (1)当l与直线x+y=0平行(不重合)时,求直线OM的斜率(2)如果|OM|=1,证明b^2=((k^2)+3)^2/((k^2)+9),并求线段AD长取最大值时
1）
l和直线x+y=0平行
k=-1
l:y=-x+b
3x^2+(b-x)^2=3
4x^2-2bx=3
x1+x2=2b/4=b/2
Mx=(x1+x2)/2=b/4
My=-Mx+b=3b/4
OM 斜率k'=My/Mx=3
2
3x^2+(kx+b)^2=3
(3+k^2)x^2+2bkx=3-b^2
x1+x2=-2bk/((3+k^2)
Mx=(x1+x2)/2=-bk/(3+k^2)
My=kMx+b=-bk^2/(3+k^2)+b
|OM|^2=Mx^2+My^2
|OM|=1
(bk)^2/(3+k^2)^2 +[-bk^2/(3+k^2)+b]^2=1
b^2k^2+b^2k^4 -2b^2k^4(3+k^2)+b^2(3+k^2)^2=(3+k^2)^2
b^2=(k^2+3)^2/(k^2+9)
3
求线段AD?长

East Asia (reporter Liu Wei) since after the NBA lockout,nike air griffey max 1, the NBA players will travel to other countries,dunk heels, "Gold Rush" speculation has abounded,ken griffey jr shoes, a...

全部展开

East Asia (reporter Liu Wei) since after the NBA lockout,nike air griffey max 1, the NBA players will travel to other countries,dunk heels, "Gold Rush" speculation has abounded,ken griffey jr shoes, and yesterday finally have conclusive information. According to Turkey,nike air max nm, local media broke the news,women griffey shoes, New Jerseys top player Deron Williams has been reached with the Turkish giants Besiktas team joining the agreement. Deron Williams signed with Besiktas is a monthly salary of 200,nike air griffey max fury,000 short-term contract,griffey shoes, the contract also specifically marked,nike air griffey max one, once the NBA lockout ended,jordan high heels, Delong can return to the NBA. Delongs choice should be just the beginning,new ken griffey shoes, then there may be more NBA player exodus to other leagues.

收起