sandy wrote:

If \(x^2 - 2xy = 84\) and \(x - y = -10\), what is the value of |y|?

Given:

x - y = -10x² - 2xy = 84Take top equation and square both sides to get:

(x - y)² = (-10)²Expand and simplify: to get:

x² - 2xy + y² = 100We now have:

x² - 2xy + y² = 100x² - 2xy = 84Subtract bottom equation from top equation to get: y² = 16

So, EITHER y = 4 OR y = -4

In both cases, |y| = 4

Answer: $

Cheers,

Brent

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Brent Hanneson – Creator of greenlighttestprep.com

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