Question

Arithmetic sequences et sn} be an arithmetic sequence that starts with an initial index of 0. The initial term is 3 and the common difference is -2. What is sz? (b) Consider the arithmetic sequence: 7, 4, 1, ... What is the next term in the sequence?

Answer 1

Answer:

(a) The value of $s_z$ is (z+1)(3-z).

(b) The next term in the sequence is -2.

Step-by-step explanation:

(a)

It is given that arithmetic sequence that starts with an initial index of 0.

The initial term is 3 and the common difference is -2.

$a_0=3$

$d=-2$

We need to find the value of $s_z$.

$s_z=\sum_{n=0}^{n=z}(a+nd)$

where, a is initial term and d is common difference.

$s_z=\sum_{n=0}^{n=z}(3-2n)$

The sum of an arithmetic sequence with  initial index 0 is

$s_n=\frac{n+1}{2}[2a+nd]$

where, a is initial term and d is common difference.

Substitute n=z, a=3 and d=-2 in the above formula.

$s_z=\frac{z+1}{2}[2(3)+z(-2)]$

$s_z=\frac{z+1}{2}[2(3-z)]$

$s_z=(z+1)(3-z)$

Therefore the value of $s_z$ is (z+1)(3-z).

(b)

The given arithmetic sequence is

7, 4, 1, ...

We need to find the term in the sequence.

In the given arithmetic sequence the first term is

$a=7$

The common difference of the sequence is

$d=a_2-a_1\Rightarrow 4-7=-3$

The first term is 7 and common difference is -3.

Add common difference in last given term, i.e., 1, to find the next term of the sequence.

$1+(-3)=1-3=-2$

Therefore the next term in the sequence is -2.