help ...please explain fully

is the answer none of these ?

 

yeps

hey esha ...now tell me how it is non of these please
 

oh sorry i couldnot chat yesterday. i logged off. i will explain. you can do this question in many ways easiest method to save time is differentiate both sides of the equation.  keeping fuction of y as constant.f ‘ (x+y)= f ‘ (x)f (y) now put x=0 and y=x . f ‘ (x)= f ‘(0)f(x) now put x=5 and find your answer. you can also use limits method .

 

its a bit lengthy (limits method) i find this method more appealing.

 

thanx esha .......i send you a friend request …....can u add me ….….….….then i can ask some questions. directly from scraps........