Question

If aand b are the 4th and 8th multiple of 3 and 7 respectively then the sum of their succesive multiple is

Answer 1

Step-by-step explanation:

1st multiple of 3 = a/4

1st multiple of 7 = b/7

sum of successive multiple

= (a/4+b/7) + 2(a/4+b/7) +3(a/4+b/7)+......

.......n(a/4+b/7)

= (a/4+b/7) ( 1+2+3+4+...........+n)

= (a/4+b/7) ( n) ( n+1) /2

=> n(n+1) (a/4+b/7) /2

This is the answer