4xy * (- x²) * (- y)³ = 4xy * x² * y³ = 4x¹⁺²y¹⁺³ = 4x³y⁴
5)А
=1/2[cos(x+x/2) +cos(x-x/2)]-1/2[cos(x-x/2)-cos(x+x/2]
=1/2[cos(x+x/2) +cos(x-x/2)-cos(x-x/2)+cos(x+x/2)]
=1/2[2cos(x+x/2)]
=cos 3x/2
2^x+2^x=11