Question

Find 8+11+14+.......+176 * 3

Answer 1

Step-by-step explanation:

8+11+14......176

so , 8,11,14.....is an AP

(where a=8 , d=3 , an=176 )

but n=?

firstly we'll find n,

an= a+(n-1)d

176 = 8 + (n-1) 3

so ....we get n as 57 ------- 1

substituting all given values in Sn formula

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

= 57/2 ( 2*8 +(57-1) *3)

=5244

therefore Sn is 5244

but (8+11+14......176)*3 is asked

( 5244)*3 = 15732

therefore. 8+11+14.......+176*3 = 15732