Question

Find the sum of the first 40 denominators divisible by 6.​

Answer 1

Step-by-step explanation:

We know that the first 40 positive integers divisible by 6 are 6,12,18,....

This is an AP with a = 6 and d = 6.

S40= 20[2(6) +(40-1)6] =20[12+234] =4920.

Answer 2

Answer:

The positive integers divisible by 6 are 6,12,18,.......

This is an example of A.P. (Arithmetic progression).

Sum of n terms of an A.P. is given by,

Sn=n/2×[2a+(n-1)d]

where,

a=first term =6

d=common difference=6

Thus,

Sn = 40/2×{2(6)+(39)6}

=20{12+234}

=20×246

=4920

Hence The Answer is 4920