What is the 20th term of the arithmetic sequence 4, -2, -8, ... ?

Feb 26, 2016

$- 110$

Explanation:

The standard $\textcolor{b l u e}{\text{ Arithmetic sequence }}$

a . a+d , a+2d , a+3d , ................, a + (n - 1 )d

where a , is the first term , d , the common difference and the nth term is a + (n-1)d

here a = 4 , d = -4-2 = -8-(-2) = -6 and n = 20

$\Rightarrow \text{ 20th term } = 4 + \left(19 \times - 6\right) = 4 - 114 = - 110$