A day full of math games & activities. Find one near you.
A day full of math games & activities. Find one near you.
A day full of math games & activities. Find one near you.
A day full of math games & activities. Find one near you.
Find the sum to n terms of the series 3 x 8 + 6 x 11 + 9 x 14 + ....
Solution:
The given series is 3 x 8 + 6 x 11 + 9 x 14 + .... n terms.
an = (nth term of 3, 6, 9 ....) x (nth term of 8, 11, 14 ....)
= (3n)(3n + 5)
= 9n2 + 15n
Therefore,
Sn = ∑nk = 1(a)k
= ∑nk = 1(9k 2 + 15k)
= 9∑nk = 1(k)2 + 15∑nk = 1(k)
= 9 x [n (n + 1)(2n + 1)]/6 + 15 x [n (n + 1)]/2
= [3n (n + 1)(2n +1)]/2 + [15n (n + 1)]/2
= 3n (n + 1)/2 x (2n + 1 + 5)
= 3n (n + 1)/2 x (2n + 6)
= 3n (n + 1)(n + 3)
NCERT Solutions Class 11 Maths Chapter 9 Exercise 9.4 Question 6
Find the sum to n terms of the series 3 x 8 + 6 x 11 + 9 x 14 + ....
Summary:
Therefore the sum to n terms of the series 3 x 8 + 6 x 11 + 9 x 14 + .... up to n terms is 3n (n + 1)(n + 3) using Sn = ∑nk = 1(a)k
Math worksheets and
visual curriculum
visual curriculum