Arithmetic Sequence Review

Given the sequence:

25, 21, 17, 13,...

Write the explicit equation that models the sequence.

• a_n = 4n + 29

• a_n = -4n + 25

• a_n = -4n + 29

• a_n = 4n + 25

Find f(26) in the arithmetic sequence: -15, -35, -55, -75, ...

*Hint: Write the explicit equation first!

• -515

• -490

• -535

• 460

A tube well is bored 800 meters deep. The 1^st meter costs $250 and the cost per meter increases by $50 for every subsequent meter. Write the explicit formula.

• 
  

  $a_n=800+50n$
  

• $a_n=250+50n$

• $a_n=250-50n$

• $a_n=200+50n$

Which of the following situations could be descried by the equation y= -25x + 120

• There are 120 people in the football stadium, and 25 more are entering each hour.
• A plumber charges $25 for a house call and $120 per hour.
• A teacher has 120 students. Her third period has 25 students
• There are 120 gallons of water in a tank. It releases water at a rate of 25 gallons per minute

Given the recursive formula below, find the explicit formula.

a₁ = 5

a_n = a_n-1 - 6

• a_n = -6n + 5

• a_n = - 6n + 11