The sum of first n natural numbers is given by 1/2 n² + 1/2 n. Find the sum of the first 11 natural numbers

Solution:

Given, the sum of first n natural numbers is given by 1/2 n² + 1/2 n

We have to find the sum of the first 11 natural numbers.

Put n = 11 in the given expression

1/2 n² + 1/2 n = 1/2 (11)² + 1/2 (11)

= 1/2 (121) + 1/2 (11)

= 1/2 (121 + 11)

= 1/2 (132)

= 66

Therefore, the sum of the first 5 natural numbers is 66.

✦ Try This: The sum of first n natural numbers is given by 1/2 n² + 1/2 n³. Find the sum of the first 12 natural numbers

☛ Also Check: NCERT Solutions for Class 7 Maths Chapter 12

NCERT Exemplar Class 7 Maths Chapter 10 Problem 86 (ii)

The sum of first n natural numbers is given by 1/2 n² + 1/2 n. Find the sum of the first 11 natural numbers

Summary:

The sum of first n natural numbers is given by 1/2 n² + 1/2 n. The sum of the first 11 natural numbers is 66

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