由x=arctant,可得
=dx dt
,1 1+t2
方程2y-ty2+et=5两边对t求导可得:
2
?y2?2tydy dt
+et=0dy dt
所以,
=dy dt
et?y2
2ty?2
所以,
=dy dx
=
dy dt
dx dt
=
et?y2
2ty?2
1 1+t2
(1+t2)
et?y2
2ty?2
t=0时有:x=arctan0=0
2y-0+1=5,y=2
=dy dx
(1+0)=1?4 0?2
3 2
即t=0时,
=dy dx
, x=0, y=23 2
所以,t=0处曲线的切线方程为y=
x+2.3 2