Hello friends ,

I am solving this question:

The sum of how may tersm of the series 6 + 12 + 18 + 24 + ... is 1800 ?

where I came across this equation n^2+n-600=0

got the values n=24 or n=25

but i dident understood how to put these values in the eqn as the answer is

ie sum of the terms = only 24

and the question is

sum of how may tersm of the series 6 + 12 + 18 + 24 + ... is 1800?

so how to calcullare sum of the terms ?

so please help me

thanks..............