Question
The maximum value of $4{\sin ^2}x + 3{\cos ^2}x$ is

Answer

b
(b) $f\,(x) = 4{\sin ^2}x + 3{\cos ^2}x={\sin ^2}x + 3$ and $0 \le \,|\sin x|\, \le 1$

$\therefore $ Maximum value of ${\sin ^2}x + 3$ is $4.$

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