How many terms of the given AP 9 , 17 ,25 ........must be taken to give sum of 636

How many terms of the given AP 9 , 17 ,25 ........must be taken to giv

1.	How many terms of the given AP 9 , 17 ,25 ........must be taken to give sum of 636
Answer» 4nsquare - 48n +53n - 6364n(n-12)+53(n-12)=n=12 12terms 4nsquare + 5n- 636=0 Divya can u plz say the quadratic equation formed here N= 12