Is |x| + |y| = 0?

Is |x| + |y| = 0?

Since absolute value is non-negative the from \(|x| + |y| = 0\) we have that the sum of two non-negative values equals to zero, which is only possible if both of them equal to zero. So, the question basically asks whether \(x=y=0\)

(1) x + 2|y| = 0. It's certainly possible that \(x=y=0\) but it's also possible that \(x=-2\) and \(y=1\). Not sufficient.

Notice that from this statement \(|y|=-\frac{x}{2}\), so \(-\frac{x}{2}\) equals to a non-negative value (\(|y|\)), so \(-\frac{x}{2}\geq{0}\) --> \(x\leq{0}\).

(2) y + 2|x| = 0. It's certainly possible that \(x=y=0\) but it's also possible that \(y=-2\) and \(x=1\). Not sufficient.

Notice that from this statement \(|x|=-\frac{y}{2}\), so \(-\frac{y}{2}\) equals to a non-negative value (\(|x|\)), so \(-\frac{y}{2}\geq{0}\) --> \(y\leq{0}\).

(1)+(2) We have that \(x\leq{0}\) and \(y\leq{0}\), hence equations from the statements transform to: \(x-2y=0\) and \(y-2x=0\). Solving gives \(x=y=0\). Sufficient.

Answer: C.

Hope it's clear.

P.S. Please read and follow: rules-for-posting-please-read-this-before-posting-133935.html