How many terms in Ap 9,17,25....must be taken to give a sum of 636

1.	How many terms in Ap 9,17,25....must be taken to give a sum of 636
Answer» See... We know a= 9 and d=8 okkk.... And the sum is given.. And we know that the formulae for geetiing the sum of aps.... So.. By using....... Sn =n/2 (2a+(n-1)d).... So now put all the values of a and d... Then... We will get the equation... 636= 5n +4n² after that u have to factorise u will get two value first in negative and second will in positive so put positive term which is........... 12.... ???? 12... Terms... Dude....

Discussion