Find the sum of n terms of the series. (4-1/n) (4-2/n) (4-3/n) . ?
Solution:-
we know that :
1 + 2 +3 + 4 +5 +6 + + n = n(n +1) / 2
and
1 + 1+ 1 + 1 + 1 + ..+ n = n
Here,
sum of 4-1/n, 4-2/n, 4-3/n up to the nth term
= (4 + 4 + 4 + 4 + 4 + .... upto n terms) + (-1/n - 2/n - 3/n - .upto n terms)
= 4 ( 1+1+1+1 upto n terms) - 1/n (1 + 2 + 3 +4 upto n terms)
= 4 n - 1/n X n(n +1)/2
= 4n - (n+1)/2
= [ 8n - (n+1) ] / 2
=( 7n - 1) / 2 Answer
Find the sum of n terms of the series. (4-1/n) (4-2/n) (4-3/n) . ?
Sum of n terms of the series:
To find the sum of n terms of the given series, we can use the concept of expansion of binomial expressions. The given series can be written as:
(4 - 1/n) * (4 - 2/n) * (4 - 3/n) * ...
Expanding the series:
Let's expand the first few terms of the given series:
(4 - 1/n) * (4 - 2/n) = 16 - 8/n - 4/n + 2/n^2
We can observe that the terms with 'n' in the denominator will cancel out when multiplied together, leaving us with:
16 - 8/n - 4/n + 2/n^2
Similarly, expanding the first three terms of the series:
(4 - 1/n) * (4 - 2/n) * (4 - 3/n) = (16 - 8/n - 4/n + 2/n^2) * (4 - 3/n)
= 64 - 32/n - 16/n + 8/n^2 - 48/n + 24/n^2 + 12/n^2 - 6/n^3
Again, we can simplify the terms with 'n' in the denominator:
64 - 32/n - 16/n + 8/n^2 - 48/n + 24/n^2 + 12/n^2 - 6/n^3
= 64 - 80/n + 44/n^2 - 6/n^3
Generalizing the pattern:
By observing the pattern in the expansion, we can generalize the terms as follows:
The sum of n terms of the series can be written as:
S(n) = 64 - 80/n + 44/n^2 - 6/n^3
Summary:
The sum of n terms of the series (4 - 1/n) * (4 - 2/n) * (4 - 3/n) can be found using the expanded form of the series. By generalizing the pattern, we obtain the formula S(n) = 64 - 80/n + 44/n^2 - 6/n^3, which represents the sum of n terms.