find the common difference in an arithmetic sequence in which a(sub 15)-a(sub7)=-1.

what should i start with ??

you add the difference 8 times to go from 7th to 15th

8 * difference = -1
difference = -1/8

To find the common difference in an arithmetic sequence, we need to first understand the given equation.

The notation "a(sub 15)" represents the 15th term of the sequence, and "a(sub 7)" represents the 7th term of the sequence.

In this case, we are given the equation: a(sub 15) - a(sub 7) = -1.

To find the common difference, we need to obtain enough information about the sequence. The difference between the 15th term and the 7th term provides us with this necessary information.

To start solving the equation, we can rewrite it in terms of the actual terms of the arithmetic sequence:

a1 + (15-1)d - [a1 + (7-1)d] = -1

Simplifying it further, we have:

a1 + 14d - (a1 + 6d) = -1

By canceling out the common terms (a1), we get:

14d - 6d = -1

Now, we can combine like terms:

8d = -1

Finally, to find the common difference, we divide both sides of the equation by 8:

d = -1/8

So, the common difference in this arithmetic sequence is -1/8.