If y = (cos x)2x. Find dy/dx.
1
\(2(\cos x)^{2x} \left (\log \cos x\, +\, x \tan x \right )\)
2
\((\cos x)^{2x} \left (\log \cos x\, +\, 2x \tan x \right )\)
3
\(2(\cos x)^{2x} \left (\log \cos x\, -\, x \tan x \right )\)
4
\((\cos x)^{2x} \left (\log \cos x\, -\, 2x \tan x \right )\)