Question

find the sum of the first 20 terms of the series 1^2+2^2+3^2


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Answer 1

Answer:

210

Step-by-step explanation:

Solution=

2

n(n+1)

here, n = 20

20(20+1)

20×21

=210

Answer 2

Answer:

The given series is that of natural numbers. Hence, we can find the sum using the relation.

$Sn = n(n + 1) \frac{1}{2} \: \: here \: n = 20 \\ S {20} = 20(20 + 1) \frac{1}{2} = 20 \times 21 \frac{1}{2} \\ S20 = 210$