Sequences
Lesson 10 of 13
Using the nth term
Objective. Test whether a number is in a sequence.
The key idea
Set the nth term expression equal to the number and solve. If n is a positive whole number, the value is in the sequence.
Worked example
Is 47 in the sequence 3n + 2?
- 13n + 2 = 47.
- 23n = 45.
- 3n = 15, a whole number.
Answer: Yes, it is the 15th term
Practice
Each question comes with a picture and a listen button. Try it first, then reveal the answer.
Common mistake. Accepting a decimal or negative value of n as a valid position.
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