Given function is f(x)=(2sinx3e)sin2x
For maxima or minima f′(x)=0
f′(x)=f(x)[2sinxcosx×ln(2sinx3e)+sin2x3e1×2sinx×23e(−sin2x1×cosx)]
⇒f(x)[sin2xln(2sinx3e)−sinxcosx]=0
Now on equation we get, sin2x=0 (not possible)
So, ln(2sinx3e)=+21
⇒2sinx3×e=e21
⇒sinx=23
⇒ {f}_\max = \left(e\right)\dfrac{3}{8} = \dfrac{{e}^{\dfrac{11}{8}}}{e} ⇒ k = e\dfrac{11}{8}
⇒(ek)8+e5k8+k8=e3+e6+e11