Question

For the arthritic sequence 5,9,13,17,21,... how many terms would you need to get to 129

Answer 1

9514 1404 393

Answer:

  32

Step-by-step explanation:

The first term is 5 and the common difference is 9-5=4, so the n-th term is ...

  an = a1 +d(n -1)

  an = 5 +4(n -1) = 4n +1

Then the term number for the term 129 is ...

  129 = 4n +1 . . . . . put the given value in the formula

  128 = 4n  . . . . . . . subtract 1

  32 = n . . . . . . . . . .divide by 4

The 32nd term is 129.