Question

The sum of the 20th term of the series 12+22+32+42+52+62 is

Answer 1

Answer:

2140 is answer

Step-by-step explanation:

a = 12

common difference = 10

n = 20

S20 = n/2 (2a+(n-1)d

=20/2 (2×12+(20-1)10

10(24+190)

= 10 × 214

= 2140

Answer 2

The sum of the 20th term of the series is 2140.

Given:

12+22+32+42+52+62+....

To Find:

The sum of the 20th term of the series.

Solution:

We are required to find the sum of the 20th term of the series.

The sum of n terms in the arithmetic progression is given as

S = n/2[2a + (n − 1) × d]  ---------(1)

The first term is, a = 12

The common difference, d = a₂-a₁ = a₃-a₂

d = 22-12

d = 10

Total number of terms, n = 20

Substitute the values of a, d, and n in equation(1)

S = 20/2[2×12+(20-1)×10]

S = 10[24+190]

S = 2140

Therefore, The sum of the 20th term of the series is 2140.

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