Q.

If y=2a2-b2tan-1[a-ba+btanx2], a,b>0, dydx|x=π2=

1 1b  
2 1a  
3 2a  
4 2b  

Ans.

(2)

y=2a2-b2tan-1(a-ba+btanx2)

dydx=2a2-b21(1+a-ba+btan2x2)sec2x2·12a-ba+b

dydx|x=π2=1a