Question

Pratham 20 visham prakritik sankhya ka Yog kya hoga​

Answer 1

Answer:

Step-by-step explanation:

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Answer 2

Step-by-step explanation:

First 20 odd natural numbers are

1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29, 31, 33, 35, 37, 39

Here a = 1

d= 3-1=2

n=20

Hence,

$sn = \frac{n}{2} (2a + (n - 1)d) \\ s20= \frac{20}{2} (2 \times 1 + (20 - 1) \times 2) \\ = 10(2 + 19 \times 2) \\ = 10(2 + 38) \\ = 10 \times 40 \\ = 400$