# What is the 20th term of the arithmetic sequence 2, –4, –10, … ?

Feb 8, 2016

After the first term you obviously subtract $6$ at every step.

#### Explanation:

At the 20th term you must have done this 19 times.
So the 20th term is $2 - \left(19 \cdot 6\right) = - 112$

Watch it!
Most of the times the first term is called ${t}_{0}$.
This means that the 20th term is then ${t}_{19}$

But if they ask you for ${t}_{20}$ (=21th) it's different:
${t}_{20} = 2 - \left(20 \cdot 6\right) = - 118$