Question

the sum of the n terms if an Ap is 5n2-3n. find the nth term and 10th term

Answer 1

the required a. p is 2,12,22,.............

Answer 2

Sn= 5n^2-3n
S1= 5(1)^2-3(1)
= 5-3
=2
S2=5(2)^2-3(2)
=5(4)-6
=20-6
=14

S2-S1=d
14-2=d
d=12

t10=a+9d
= 2+9(12)
=2+108
=110