Review question

Ref: R9468

## Question

The first term of an arithmetic sequence is $a$ and the common difference is $d$.

The sum of the first $n$ terms is denoted by $S_n$.

If $S_8>3S_6$, what can be deduced about the sign of $a$ and the sign of $d$?

1. both $a$ and $d$ are negative

2. $a$ is positive, $d$ is negative

3. $a$ is negative, $d$ is positive

4. $a$ is negative, but the sign of $d$ cannot be deduced

5. $d$ is negative, but the sign of $a$ cannot be deduced

6. neither the sign of $a$ nor the sign of $d$ can be deduced