x^2/16+y^2/9=1
x=2 , y= 3√3/2 or y= -3√3/2
x^2/16+y^2/9=1
两边求导
d/dx (x^2/16+y^2/9)=0
(1/8)x + (2/9)y.y' =0
y' = -(9/16)(x/y)
y'|(x,y) = (2, 3√3/2) = -√3/4
y'|(x,y) = (2, -3√3/2) = √3/4
切线方程 (2, -3√3/2)
y+3√3/2 =-(√3/4)(x-2)
切线方程 (2, 3√3/2)
y-3√3/2 =(√3/4)(x-2)