Retired Moderator
Joined: 07 Jun 2014
Posts: 4815
Given Kudos: 0
WE:Business Development (Energy and Utilities)
Re: If x – y = and x2 – y2 = 3, what is the value of x + y?
[#permalink]
28 Jul 2018, 16:09
Explanation
The Difference of Squares (one of the “special products” you need to memorize for the exam) is \(x^2 - y^2 = (x + y)(x - y)\).
Write this pattern on your paper and plug in the given values, solving for x + y:
\(x^2 - y^2 = (x + y)(x - y)\)
\(3 = (x + y)(\frac{1}{2})\)
\(6 = x + y\)