|
|
|
|
|
 Discussion Response Post to:
f(x+y)=f(x)f(y) ,,,,f(5)=2,,,f'(0)=3,,,f'(5) is what
|
| Author |
Message |
![[Post New]](/templates/default/images/icon_minipost_new.gif) 22 May 2008 23:14:06 IST
Subject: f(x+y)=f(x)f(y) ,,,,f(5)=2,,,f'(0)=3,,,f'(5) is what
|
|
|
put x=0 y=0 in the given expression ull get f(0)= f(0)^2
so either f(0)=0 or f(0)=1
but since f(0) cannot be zero therefore f(0)=1
now assume x to be constant and differentiate wrt to y
ull get f'(x+y) = f(x)f'(y)......1
now assume y to be constant and diff wrt to x
f'(x+y)=f'(x) f(y).............2
equating 1 and 2
f(x) f'(y)= f'(x) f(y)
put x=0 y =5
and substitute the given values ull get f'(5)=6
|
this reply: 2 points
(with 0 
in 1 votes ) [?]
|
|
You have to be logged on to rate
|
|
|
|
|
|
|
|
|
|
Moderation Team
![[Up]](/templates/default/images/icon_up.gif "[Up]"){kind=icon}
