Given the arithmetic sequence, what is a18? 18,14,10 A18=
Mathematics · High School · Tue Nov 03 2020
Answered on
Given the arithmetic sequence:
18,14,10
Determine A18
n=18
Formula for arithmetic sequence: An = a1 + (n-1)d
Solution:
In order to determine A18, we must look first for the common difference in the given terms. We can do this by subtracting the 1st term to the 2nd term.
First Term = 18
Second term = 14
Third Term = 10
Common Difference = Second term - First term
Common Difference = 14 -18
Common Difference = -4
Now what we have the common difference, we can now easily solve the equation, by substituting the values to the formula for arithmetic sequence.
An = a1 + (n-1)d
A18 = 18 + (18-1) -4
A18 = 18 + (17)-4
A18 = 18 -68
A18 = -50
Final answer: A18= -50