If x is a real quantity, what is the minimum value of $\left(25 \cos ^2 x+9 \sec ^2 x\right)$
Answer & explanation
Correct answer: option 1
Concept we are using here is :-
If we are given acos²x + bsec²x , then
Minimum value of acos²x + bsec²x is 2\(\sqrt {ab }\).
ATQ,
Minimum value of
25cos²x + 9sec²x
= 2\(\sqrt {25 ×9 }\)
= 30