Evaluating an infinite series Write the Taylor series for f(x) = 1n (1 + x) about 0 and find the interval of convergence. Assume the Taylor series converges to / on the interval of convergence. Evaluate /(I) to find the value of (the alternating harmonic series).
Solution 47E
Step 1:
Given that
f(x) = 1n (1 + x) about 0
(the alternating harmonic series).
Step2:
To find
Write the Taylor series for f(x) = 1n (1 + x) about 0 and find the interval of convergence. Assume the Taylor series converges to / on the interval of convergence. Evaluate /(I) to find the value of
Step3:
We have
f(x) = 1n (1 + x)
Taylor serie for f(x) = 1n (1 + x)
In(1+x)=x-
We know that series converges when |x|<1 and diverges when |x|>1
Now we have to check x=
So, the interval of convergence is (-1,1)
The equation
In(x+1)=
Is true for x=1
So, put x=1 we get
In(2)=
That is the sum of the alternating harmonic series is In2.