Question

the sum of the first 15
multiples of 8 is ​

Answer 1

Answer:

960

Step-by-step explanation:

8+16+24+32+40+48+56+64+72+80+88+96+104+112+120= 960

Answer 2

$\huge\purple{\mid{\fbox{\tt{Answer࿐}}\mid}}$

First 15 multiples of 8 are

8 + 16+ 24 + . . . . . . . . . 120 This is an AP with common difference(d)= 8, first term 'a' = 8 & last 15 th term (L) = 120

The sum of the terms of an AP

$\pink\longrightarrow$N/2 ( a + L)

$\pink\longrightarrow$15/2 ( 8 + 120 )

$\green\longrightarrow$15/2 * 128

$\green\longrightarrow$ 15* 64

$\pink\longrightarrow$960