JEE Advance - Mathematics (1990 - No. 24)
Show that $$2\sin x + \tan x \ge 3x$$ where $$0 \le x < {\pi \over 2}$$.
The inequality holds trivially at x = 0.
Using Taylor series expansion, $$2sin x = 2(x - rac{x^3}{3!} + O(x^5))$$ and $$ an x = x + rac{x^3}{3} + O(x^5)$$.
Therefore, $$2sin x + an x = 3x - rac{x^3}{3} + rac{x^3}{3} + O(x^5) = 3x + O(x^5)$$.
Since the higher-order terms are non-negative for $$0 le x < {pi over 2}$$, the inequality holds.
The provided argument is incorrect or incomplete and further analysis is needed.
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