Solve the following
Question:

If $5\left(\tan ^{2} x-\cos ^{2} x\right)=2 \cos 2 x+9$, then the value of $\cos 4 x$ is :-

1. $-\frac{7}{9}$

2. $-\frac{3}{5}$

3. $\frac{1}{3}$

4. $\frac{2}{9}$

Correct Option: 1

Solution: