Question

The sum of first three terms of an arithmetic series is 21. If the sum of the first two terms is subtracted from the third term then it would be 9. find the three terms of the series​

Answer 1

The terms are - 1, 7 and 15.

Explanation:

Let the terms be a-d, a and a+d

ATQ, a-d+a+a+d=21, a=7. a+d-(a+(a-d))=9. d=8. The terms are - 1, 7 and 15.