JEE MAIN - Mathematics Hindi (2017 (Offline) - No. 8)

यदि $$5\left(\tan ^{2} x-\cos ^{2} x\right)=2 \cos 2 x+9$$, तो $$\cos 4 x$$ का मान है :

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

$$\frac{2}{9}$$

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

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