Find the Next Term in Arithmetic Sequence: -15, -17, -19, -21, ?

To solve this problem, we'll follow these steps:

• Step 1: Identify the pattern in the sequence.
• Step 2: Calculate the common difference.
• Step 3: Use the common difference to find the next term in the sequence.

Step 1: Look at the given sequence: $-15, -17, -19, -21$.
To find the common difference, we can subtract each term from the next one. For example, the difference between $-15$ and $-17$ is:

$-17 - (-15) = -17 + 15 = -2$

Similarly, between $-17$ and $-19$, and $-19$ and $-21$, we have:

$-19 - (-17) = -2$

$-21 - (-19) = -2$

Step 2: We have determined that the common difference $d$ is $-2$.

Step 3: To find the next term, subtract the common difference from the last term: $-21 - 2 = -23$.

Therefore, the next number in the sequence is $-23$.