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Algebra Difficulty 3.1 AMC 10/12 Find the answer

Real numbers xx, yy, and zz satisfy the inequalities
0<x<10<x<1, 1<y<0-1<y<0, and 1<z<21<z<2.
Which of the following numbers is necessarily positive?

Pick one

Solution

Notice that y+zy+z must be positive because z>y|z|>|y|. Therefore the answer is (E) y+z\boxed{\textbf{(E) } y+z}.
The other choices:
(A)\textbf{(A)} As xx grows closer to 00, x2x^2 decreases and thus becomes less than yy.
(B)\textbf{(B)} xx can be as small as possible (x>0x>0), so xzxz grows close to 00 as xx approaches 00.
(C)\textbf{(C)} For all 1y2-1|y^2|, and thus it is always negative.
(D)\textbf{(D)} The same logic as above, but when 12<y<0-\frac{1}{2}<y<0 this time.

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Source: NuminaMath-1.5, licensed Apache-2.0. Statement and solution reproduced as published; topic and difficulty added by this site.