What is the sum of following series if, the number of terms is 192.

4 + (-8) + 9 + (-10) + 11 + (-12) + ..... = ?

I can see that it is neither an arithmetic nor a geometric sequence.

Starting from n=2, taking every other n makes a sequence.

Starting at n=3, taking every other n after that also makes a sequence.

But I still can't figure out how to get to the solution. The sum is supposed to be -99.

4 + (-8) + 9 + (-10) + 11 + (-12) + ..... = ?

I can see that it is neither an arithmetic nor a geometric sequence.

Starting from n=2, taking every other n makes a sequence.

Starting at n=3, taking every other n after that also makes a sequence.

But I still can't figure out how to get to the solution. The sum is supposed to be -99.

Last edited: