Calculus questions

Could someone please solve the questions given below :

Evaluate:
n-->infinity\sum_{r=1}^{n}\frac{r}{4r^2+1}

Prove that if
f(x)=lim\, n--->infinity(x^{1/n}-1)

then f(xy)=f(x)+f(y)

the second questions seems incorrect to me

4 Answers

19
Debotosh.. ·

for the first one ,,,put it in the form of f(r/n) ....after doing that we get this as
0∫1 (x) / (4x2 + 1)....replacing r/n =x in the equation obtained earlier !

19
Debotosh.. ·

second one looks a bit funny and really simple if thought simply ;);)
what we know is hat if x,y are independent variables then f(xy) = f(x) + f(y) implies f(x)=klnx or f(x) =0........here it is straightforward that f(x)=0..hence condition satisfied !

1
anantc ·

The first question is incorrect.The series is divergent.

62
Lokesh Verma ·

debotosh, but the denominator is not n^2

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