Question

find the sum of first 30terms of the sequence 5,10,15,20,..​

Answer 1

Answer:

2325

Step-by-step explanation:

The terms, 5, 10, 15, 20... are in AP

Formula => Sum of AP = n/2 (2a + (n - 1)d)

Here:

n is number of terms, a is first term, and d is common difference.

n = 30

d = 10 - 5 = 5

a = 5 (first term)

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

=> 30/2 (2 × 5 + (30 - 1)5)

=> 15 (10 + 29 × 5)

=> 15 (10 + 145)

=> 15 (155)

=> 2325

Sum = 2325

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Answer 2

Hence , sum of first 20 terms is 1050

refer image xD xD