Question

Helpo me if you know the answers

Answer 1

Given:

The nth term of a number sequence is $n^2+2n$.

To find:

The first 3 terms and the 10th term.

Solution:

We have, nth term of a number sequence.

$a_n=n^2+2n$

For n=1,

$a_1=(1)^2+2(1)$

$a_1=1+2$

$a_1=3$

For n=2,

$a_2=(2)^2+2(2)$

$a_2=4+4$

$a_2=8$

For n=3,

$a_3=(3)^2+2(3)$

$a_3=9+6$

$a_3=15$

For n=10,

$a_{10}=(10)^2+2(10)$

$a_{10}=100+20$

$a_{10}=120$

Therefore, the first three terms are 3, 8 and 15 respectively. The 10th term is 120.