This topic mainly investigates the solution of absolute value inequality when absolute value triangles are not equal, which embodies the mathematical idea of reduction and classification discussion and belongs to an intermediate topic. Although this topic is short, it is not difficult. Here are the answers. Take a closer look. Ask if you don't understand.

The answer is here /exercise/math/804057 function f (x) = | x+ 1/a |+| x-a | (a > 0).

(i) prove that f (x) ≥ 2;

(ii) If f (3) < 5, what is the range of a?

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