Differentiate the following functions with respect to x :
4x+5 sin x3x+7 cos x
Let y=4x+5 sin x3x+7 cos x
Differentiating y w.r.t. x, we get
dydx=(3x+7 cos x)ddx(4x+5 sin x)−(4x+5 sin x)ddx(3x+7 cos x)(3x+7 cos x)2 (By quotient formula)
=(3x+7 cos x)(4×1+5 cos x)−(4x+5 sin x)(3−7 sin x)(3x+7 cos x)2
=12x+15x cos x+28 cos x+35 cos2x−12x+28 x sin x−15 sin x+35 sin2x(3x+7 cos x)2
=35(cos2x+sin2x)+15 x cos x+28 cos x+28 x sin x−15 sin x(3x+7 cos x)2
=35+15 x cos x+28 cos x+28 x sin x−15 sin x(3x+7 cos x)2 [∵ sin2x+cos2=1]