How should I solve the following inequality?

u+vu+v|u|+|v| \geq u+v
That's clearly what you are intended to notice; they designed the problem carefully. But, of course, most problems that look similar to this one would either need a different related inequality, like u+vuv|u|+|v| \geq u-v, or would require a general method such as I suggested.

So my answer is perhaps better for the general question as asked, "How should I solve such an inequality that contains multiple absolute values?", but yours is far more insightful for the particular questions.
 
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