By the Derivative Difference Rule
#(d (3*sqrt(x) - sqrt(x^3)))/(dx) = color(red)((d (3*sqrt(x)))/(dx)) - color(blue)((d(sqrt(x^3)))/(dx)#
#color(red)((d (3*sqrt(x)))/(dx) = (d (3*x^(1/2)))/(dx))#
#color(red)(=3/2* x^(-1/2))#
#color(blue)((d(sqrt(x^3)))/(dx) = (d (x^(3/2)))/(dx))#
#color(blue)=(3/2*x^(1/2))#
#(d (3*sqrt(x) - sqrt(x^3)))/(dx) = color(red)(3/2*1/sqrt(x))-color(blue)(3/2*sqrt(x))#
#= 3/2(1/sqrt(x)-sqrt(x))#