直线l交椭圆x^2/16+y^2/12=1于A,B两点,AB的中点为M(2,1),则l的方程为( )A.2x-3y-1=0B.3x-2y-4=0C.2x+3y-7=0D.3x+2y-8=0

直线l交椭圆x^2/16+y^2/12=1于A,B两点,AB的中点为M(2,1),则l的方程为( )A.2x-3y-1=0B.3x-2y-4=0C.2x+3y-7=0D.3x+2y-8=0
直线l交椭圆x^2/16+y^2/12=1于A,B两点,AB的中点为M(2,1),则l的方程为( )
A.2x-3y-1=0
B.3x-2y-4=0
C.2x+3y-7=0
D.3x+2y-8=0

直线l交椭圆x^2/16+y^2/12=1于A,B两点,AB的中点为M(2,1),则l的方程为( )A.2x-3y-1=0B.3x-2y-4=0C.2x+3y-7=0D.3x+2y-8=0
设直线交椭圆与A,B两点.
A(x,y),B(4-x,2-y)
所以x^2/16+y^2/12=1 ①
(4-x)^2/16+(2-y)^2/12=1 ②
①-②：x^2-(x^2-8x+16)/16+y^2-(y^2-4y+4)/12=0
(8x-16)/16+(4y-4)/12=0
(x-2)/2+(y-1)/3=0
3x-6+2y-2=0
3x+2y-8=0
不懂发消息问我.