Solve the Sequence Formula n²-n: Finding the Fifth Element

Question

Below is the rule for a sequence written in terms of $n$ :

$n^2-n$

What is the 5th element?

00:00 Find the 5th element

00:03 Position of the desired element according to the data

00:11 Substitute appropriate values according to the data and solve to find the element

00:18 Always solve exponents first

00:27 And this is the solution to the question

To solve this problem, we will follow these steps:

Now, let's work through each step:

Step 1: We have the formula for the sequence as $a_n = n^2 - n$ .

Step 2: We will substitute $n = 5$ into the formula:

$a_5 = 5^2 - 5$

Step 3: Calculate the expression:

$a_5 = 25 - 5$

$a_5 = 20$

Therefore, the 5th element of the sequence is $20$ .

$20$