Question

In a certain arithmetic sequence, a5=12 and a6=16. What is a1?

Answer 1

Step-by-step explanation:

The nth term of an arithmetic sequence is obtained using the formula:

`a_n=a_1+(n-1)d`

Given the following:

`\begin{gathered} a_5=12\implies a_1+4d=12 \\ a_6=16\implies a_1+5d=16 \end{gathered}`

Subtracting, we have: