Asked by Anonymous

The first term of an arithmetic progression is 7 and the 100th term is 502. Find the sum of the first 50 terms.
Answered by oobleck
7+99d = 502
50/2 (14+49d) = _____
Answered by Anonymous
Not understanding what you just did oobkeck
Answered by oobleck
In that case, you need to review APs, and the formula for the sum of the first n terms -- which I gave you. I just wrote the facts they gave in algebra.

Find d, then use it in the formula.