Find the nth term of the sequence 3,7,11,15...

We are searching for a rule that when we put in n (n represetning where the term is in the sequence eg. 3 is the first term so n will be 1) our output is the sequence above. This rule will most likely be in the form an+b. Let's begin by finding a. a can be found by calculating the steps that the sequence makes from term to term, in this case 4. This means that each input n is being multiplied by 4 to reach to output. However now if we put in 1 to 4n we have an output of 4 not 3. How do we get from 4 to 3 or 8 (2x4) to 7? -1. Therefore our b must be -1 to make our rule true for the sequence we have been given. Our nth term is therefore 4n-1.

JS
Answered by Joanna S. Maths tutor

32972 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

Write 870,000,000 in standard form


Calculate the largest share when £400 is shared in the ratio 1 : 2 : 5.


There are 10 balls in a bag. The balls are the same apart from their colour. Of the 10 balls, 3 are black, 5 white, 2 red. What is the probability of picking a white ball from the bag.


I feel really nervous about time pressure in the exam, I don't think I'll finish


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

MyTutor is part of the IXL family of brands:

© 2025 by IXL Learning