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Course: Class 10 (OD) > Unit 3

Lesson 3: nth term of an AP
Math
Class 10 (OD)
Arithmetic progressions
nth term of an AP
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nth term of an arithmetic progression (intermediate)

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Problem

In an arithmetic progression,
an−a9=12
The common difference is 3.
Find the value of n.
n=
  • Your answer should be
  • an integer, like 6
  • a simplified proper fraction, like 3/5
  • a simplified improper fraction, like 7/4
  • a mixed number, like 1 3/4
  • an exact decimal, like 0.75
  • a multiple of pi, like 12 pi or 2/3 pi