differentiation

let f(x/2+y/2)=f(x)/2+f(y)/2 , x,y belongs to real no.
f ' (0) exists and is equal to -1 and f(0)=1 , then find the value of f(2)

9 Answers

1
ith_power ·

put y=0;
f(x/2)=f(x)/2 + 1/2.
f(x)=f(2x)/2 + 1/2.

f'(x)=lim h→0 (f(2x)/2+f(2h)/2-f(x))/h = lim h→0 (f(h)-1/2 - 1/2)/h
=f'(0)=-1.

f(x)=-x+c

f(0)=0 so c=1.

f(x)=1-x...

1
Rohan Ghosh ·

-1

1
Rohan Ghosh ·

i saw f'(0)=1 first!!

1
big looser ......... ·

how step 6 comes f(x) =c-x

1357
Manish Shankar ·

f'(x)=-1
implies
f(x)=-x+c

1
big looser ......... ·

ok , may be i m confused but where it is given that f'(x)=-1

1357
Manish Shankar ·

He proved in the above steps
f'(x)=f'(0)=-1

1
big looser ......... ·

ok now i got it. thanks

1
Nikee Bole ·

Diffrentiate the following
y=Sec-1(1+x4)

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