The first four terms of an arithmetic sequence are: 3, 10, 17, 24. What is an expression, in terms of n, for the nth term?

Before we start thinking about an expression for this sequence, we need to figure out what's going on. An arithmetic sequence means that there's a certain number being added on each time. By working out the difference between these numbers we can see that here the number being added is 7 (for example 10-3=7). So now we need to write our expression. This is just a way of showing someone what a sequence is without having to write it all out for them. It will be of the form d.n+a (try remembering it using DNA from science), where "d" and "a" are what you need to find out. The first one is easy: "d" stands for difference and we've already worked out that is 7.To work out "a", siimply substract the difference, 7, from the first number in the sequence (called the first "term"), which is 3. 3-7=-4, so "a" is -4.You can conclude that the expression is 7n-4.

Answered by Ed W. Maths tutor

18863 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

Solve the equation ((x^2+2)^2)/x^2=9


Rearrange the following equation to make 'm' the subject: 4 (m - 2) = t (5m + 3) [4 marks]


Solve 2x+y=6, 3x+2y=3 for x and y.


There are 10 boys and 20 girls in a class. The class has a test. The mean mark for all the class is 60. The mean mark for the girls is 54. Work out the mean mark for the boys.


We're here to help

contact us iconContact usWhatsapp logoMessage us on Whatsapptelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2024

Terms & Conditions|Privacy Policy