Question

15. Find the sum of first 30 positive integers divisible by 6.

Answer 1

Answer:

2790

Step-by-step explanation:

step 1 Address the formula, input parameters & values.

Input parameters & values:

The number series 6, 12, 18, 24, 30, 36, 42, 48, 54, 60, .  .  .  .  , 180.

The first term a = 6

The common difference d = 6

Total number of terms n = 30

step 2 apply the input parameter values in the AP formula

Sum = n/2 x (a + Tn)

= 30/2 x (6 + 180)

= (30 x 186)/ 2

= 5580/2

6 + 12 + 18 + 24 + 30 + 36 + 42 + 48 + 54 + 60 + .  .  .  .   + 180 = 2790

Therefore, 2790 is the sum of first 30 positive integers which are divisible by 6.

Answer 2

Answer:

2790

Step-by-step explanation:

n = 30

d= 6

a = 6

using formula of Sn

Sn= n/2[2a +( n-1) d]

Sn 30/2[ 2(6)+(30-1)6]

Sn =15(12+174)

Sn= 15(186)

Sn=2790

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