It’s always a nice feeling, not just in maths, when you give an answer and you know it is correct. Let’s do the fourth term as well, we know this should be 12… N = 1 1 2 – 2×1 + 4 = 1 – 2 + 4 = 3 this matches our sequence! This allows us to check the formula we calculated is correct. Likewise, we know that the second term in the sequence is 4, so if we plug 2 into the formula we should get 4.
So, if we plug 1 into the formula we should get 3. We know from the question that the first term in the sequence is 3. The calculator will generate all the work with detailed explanation. Also, it can identify if the sequence is arithmetic or geometric. The main purpose of this calculator is to find expression for the n th term of a given sequence. Going back to why the nth term formula is useful, remember that the formula tells you any term in the sequence. N th term of an arithmetic or geometric sequence. What I would strongly recommend at this stage is that you check your answer. So the nth term of the green sequence is -2n + 4.Īdding this on to what we already knew, this means our nth term formula is n 2 – 2n + 4. The sequence has a difference of -2, and if there were a previous term it would be 4.
Quadratic sequences formula how to#
If you need a reminder of how to find the nth term of a linear sequence, you can re-read the previous blog. We will need to add this on to n 2 – this will tell us our b and c. What we now need to do is find the nth term of this green sequence. You need to substitute the value of n into the formula. This sequence should always be linear – if it isn’t, you have done something wrong. To work out terms in a quadratic sequence, you follow the same rules as you would for a linear sequence. The differences between our sequence and the sequence n 2 now forms a linear sequence (in green above).
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