Question

a=4,d=2,sum of n terms(sn) =-14 find n and an

Answer 1

And=n/2[2a+(n-1)d]=> -14=n/2[2*4+(n-1)2]=> -28=n[8+2n-2] => -28 = 2n(3+n) => -14 = 3n + n^2 => n^2 +3n +14 =0 Solve the quadratic equation and you will get the answer