Question

6. Find the sum of first 15 multiplies of 8.​

Answer 1

Answer:

Sum of first 15 multiples of 8 is 960

Step-by-step explanation:

First Term (a) = 8

Common Difference (d) = 8

Number of terms (n) = 15

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

Sn = 15/2 [2(8) + 14(8)]

Sn = 15/2 [16 + 112]

Sn = 15/2 [128].

Sn = 15 [64]

Sn = 960.....

So, Sum of first 15 multiples of 8 is 960

Answer 2

Answer:

Then, the sum of the first 15 multiples of 8 =152×(8+120)=152×128=960. Thus, the sum of the first 15 multiples of 8 is 960.