Question

13. The sum of n natural numbers is 5n2 + 4n.
Find its gth term.​

Answer 1

Answer

10g-1

Step-by-step explanation:

S1=a1

=a

=5(1)²+4(1)

=5+4

=9

S2 =a1+a2

5(2)²+4(2)=9+a2

20+8=9+a2

28-9=a2

a2=19

d=a2-a1

= 19-9

=10

ag= a+(g-1)d

=9+(g-1)10

=9+10g-10

=10g-1