Question

if the sum of n terms of an ap is given by Sn=n^2-3n find the 2nd term and 10 th term

Answer 1

Step-by-step explanation:

Sn = n^2-3n

S1 = 1^2-3= 1-3 = -2 =A1

S2 = 2^2-3(2) = 4-6= -2

Now A2 = S2-S1

A2 = -2-(-2) = 0

So A1 = -2 and A2 = 0

so common difference d = 0-(-2)=2

Here second term A2 = 0

and 10th term = A1+9(common difference)

= -2+9(2)

= 16