# Arithmetic Sequences Problem

• Nov 30th 2011, 07:12 AM
MalevolentSpoon
Arithmetic Sequences Problem
"Find three consecutive terms of an arithmetic sequence if their sum is 3 and their product is -15"

I know the answer is -3,1,5 but I pretty much just guessed that on a fluke. What is the method of answering this question? I don't think I'll get the marks unless I use a method of some sort :(
• Nov 30th 2011, 07:35 AM
Quacky
Re: Arithmetic Sequences Problem
Let \$\displaystyle a\$, \$\displaystyle (a+d)\$, and \$\displaystyle (a+2d)\$ be the three consecutive terms, where \$\displaystyle d\$ is the common difference. Set up simultaneous equations for \$\displaystyle a\$ and \$\displaystyle d\$.
• Nov 30th 2011, 11:22 AM
MalevolentSpoon
Re: Arithmetic Sequences Problem
Quote:

Originally Posted by Quacky
Let \$\displaystyle a\$, \$\displaystyle (a+d)\$, and \$\displaystyle (a+2d)\$ be the three consecutive terms, where \$\displaystyle d\$ is the common difference. Set up simultaneous equations for \$\displaystyle a\$ and \$\displaystyle d\$.

Thanks! It makes sense now :)