Question

Find the 15th term of this arithmetic sequence for 20,26,32,38,44

Answer 1

Answer:

104

Step-by-step explanation:

There are two ways to do it, though we need to know how it is affected.

20+6=26

26+6=32

32+6=38

38+6=44

Thus, you are adding 6 for each term.

1. You do it manually...(yes.)

I'll number it one by one

1.20

2.26

3.32

4.38

5.44

6.50

7.56

8.62

9.68

10.74

11.80

12.86

13.92

14.98

15.104

The 15th term is 104.

2. This method is easier. As shown above, there is a pattern. We can apply it using this formula:
20+6(n-1)

You can get this formula from the facts that:
-you start off with an additional added 8

-you add 6 every time

-if we do it 6n then it would be incorrect, with an extra 6 for each

-the formula is correct; you can test it for terms 2,3,4,5 like this:

20+6=26

20+2x6=32

20+3x6=38

20+4x6=44

To find the 15th term, you can:

20+14x6=20+84=104.