Question

Consider the arithmetic sequence 3,8,13,18 find S15

Answer 1

Answer:

This is an arithmetic sequence since there is a common difference between each term. In this case, adding  

5

to the previous term in the sequence gives the next term. In other words,  

a

n

=

a

1

+

d

(

n

−

1

)

.

Arithmetic Sequence:  

d

=

5

This is the formula of an arithmetic sequence.

a

n

=

a

1

+

d

(

n

−

1

)

Substitute in the values of  

a

1

=

3

and  

d

=

5

.

a

n

=

3

+

(

5

)

(

n

−

1

)

Simplify each term.

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a

n

=

3

+

5

n

−

5

 

Subtract  

5

from  

3

.

a

n

=

5

n

−

2

Step-by-step explanation: