1ANS...7/3 ???
f(x) be a continous and differentiable function. f(y)f(x+y)= f(x) f(5) = 3 and f'(3)=7 then f'(8) = ........
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3 Answers
29f(x+y) = f(x) / f(y)..
Taking x as variable and y as constant..and differentiating wrt x we get..
f'(x+y) = f'(x) / f(y)
Now putting y = 5 and x = 3..
f'(8) = f'(3) / f(5)
= 7/3....
1ANS IS 7/3.
BUT IN UR ANS GOVIND, IF QUESTION HAD GIVEN ANOTHER DATA THAT f'(4) = 9[let]
THEN U COULD HAVE USED y = 5 and x= 4,
then ANS WOULD HAVE BEEN 9/3 = 3 SHOULDN'T f'(8) HAVE A CONSTANT VALUE......