Thread: AP prob

the sum of n terms of an AP is . Find the number of terms which equals

Originally Posted by banku12

the sum of n terms of an AP is . Find the number of terms which equals

hi

T_n=a+(n-1)d=159 ---1

We need to find a and d .

a=S1=3(1)^2+5=8





=9

so a=8 , and the common difference , d=1 . Now substitute into 1 to find n .