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An arithmetic sequence has a common difference of 5 and the 3rd term is 15. What is the 5th term?

Please help me!

User Xxyyxx
by
4.5k points

1 Answer

10 votes

Answer:

an=8n−14

Explanation:

for an AP

where

a

1

=

the first term

d

=

the common difference

then we have

a

1

,

(

a

1

+

d

)

,

(

a

1

+

2

d

)

,

...

,

a

1

+

(

(

n

1

)

d

)

,

.

.

we are given the third term

10

=

a

1

+

2

d

(

1

)

and the fifth term

26

=

a

1

+

4

d

(

2

)

subtract

(

2

)

(

1

)

16

=

2

d

d

=

8

sub into

(

1

)

10

=

a

1

+

2

×

8

a

1

=

6

so the nth term

a

n

=

a

+

(

n

1

)

will be

a

n

=

6

+

8

(

n

1

)

a

n

=

8

n

14

User Hejazi
by
4.9k points