Question

sum of n natural no.s is 5n square + 4n. Find its 8th term.

Answer 1

Answer:

64

Step-by-step explanation:

In AP,

nth term = sum of n terms - sum of (n - 1) terms

Sum of n natural numbers is 5n² + 4n.

So,

8th term = ( sum of 8 terms ) - ( sum of 7 terms )

= > { 4(8)² + 4(8) } - { 4(7)² + 4(7) }

= > { 4(64) + 32 } - { 4(49) + 28 }

= > 4(64) + 32 - 4(49) - 28

= > 4(64) - 4(49) + 32 - 28

= > 4(64 - 49) + 4

= > 4(15) + 4

= > 60 + 4

= > 64