Arithmetic and Geometric Sequences

Mixed Sequences

100

Write the formula for the sequence: 12, 14, 16, 18, 20, .....

a_n=12 +2(n-1)

200

Write the formula for the sequence: 3, 8, 13, 18, 22, .....

a_n=3 + 5(n-1)

300

Write the formula for the sequence: 4, 20, 100,  ....

a_n=4(5)^n-1

400

Write the formula for the sequence 375, 75, 15, 3, ...

a_n=375(1/5)^n-1

Arithmetic

100

This is the value of the 60th term when the 1st term is 5 and the common difference is -5.

What is -290?

200

The value of the 1st term when the 23rd term is 36 and the common difference is 2.

What is -8?

300

The first term is 4 and the second term is -4. Write the formula for the arithmetic sequence.

a_n=4-8(n-1)

400

The first term is 4 and the third term is 10. Write the formula for the arithmetic sequence.

a_n=4+7(n-1)

Modeling

100

A bank account has $50 during the first week. You add $10 to your account every week. Write the formula to model the amount of money in your account.

a_n=50+10(n-1)

200

There are 4 rabbits in the zoo in the first month. The number of rabbits doubles each year. Write the formula to model the number of rabbits in the zoo.

a_n=4(2)^n-1

300

The current population in New City is 10,000. Every year, the population increases by 50 people. Write the formula to model the population.

a_n=10050+50(n-1)

400

The current amount in your bank account is $100. Every month you deposit $75 in the the account. Write the formula to model the amount in your account. 

a_n=175+75(n-1)

Find the Missing term(s)

100

Find the missing term in the following Arithmetic sequence. 3, ___ ,17

What is 10?

200

Find the missing term in the following Geometric sequence. 2, ____, 128

What is 16?

300

Find the missing term in the following Arithmetic sequence. -13, ___ ,-27

What is -20?

400

Find the missing terms in the following Arithmetic sequence. 10, ____, ____ , _____, 26

What is 14, 18, 22?

Geometric

100

Write the formula if the first term is 20 and the common ratio is -3.

a_n=20(-3)^n-1

200

Write the formula for the sequence: 80, 40, 20,...

a_n=80(1/2)^n-1

300

The first term is 4 and the second term is 20. Write the formula for the geometric sequence.

a_n=4(5)^n-1

400

The first term is 2 and the second term is 72. Write the formula for the geometric sequence.

a_n=2(36)^n-1