Question

( begin{array}{l}text { Solve } qquad begin{aligned} & operatorname{Cos} 4 x =&left.log _{2}(2 x)right} &=2 log _{2 x-1}left(1 cdot cos 2 theta=2 cos ^{2} theta-1right. &=2left(2 cos ^{2} x-1right)^{2}-1 end{aligned} & =2,left(4 cos 4 x+1-4 cos ^{2} xright]-1 & =8 cos 4 x-8 cos ^{2} x+2-1 & =8 cos ^{4} x-8 cos ^{2} x+1end{array} )

# tend the value of cos 4x Fing y by x, we sin (x + 2site sin 2x = cos x+.

Solution