Question

Question 1 Write the first five terms of the sequences whose nth term is an = n(n+2)

Class X1 - Maths -Sequences and Series Page 180

Answer 1

I am in class 10th so I can do it in a easy manner.

an=n (n+2)
let n=1 , a1=1 (1+2)=3
let n=2, a2=2 (2+2)=8
let n=3, a3=3 (3+2)=15
let n=4, a4=4 (4+2)=24
let n=5, a5=5 (5+2)=35

Ans:-First five terms of the sequence are:-3,8,15,24,35

if we subtract them I. e.
8-3=5,15-8=7,24-15=9,35-24=11
HOPE THIS ANSWER HELPS

Answer 2

aₙ = n( n + 2)
= n² + 2n

first term = a₁ = (1)² + 2(1) = 1 + 2 = 3
2nd term = a₂ = (2)² + 2(2) = 4 + 4 = 8
3rd term = a₃ = (3)² + 2(3) = 9 + 6 = 15
4th term = a₄ = (4)² + 2(4) = 16 + 8 = 24
5th term = a₅ = (5)² + 2(5) = 25 + 10 = 35