Differentiate.

1. $\frac { d } { d x } ( 7 \cdot \sqrt [ 3 ] { x } )$

   Hint (a):

   Before differentiating, rewrite with a fractional exponent.

2. $\frac { d } { d m } ( 3 m ^ { - 7 } - 7 m ^ { 3 } )$

   Hint (b):

   Differentiate $3m^{−7}$ and $−7m^{3}$ separately.

   Answer (b):

   $−21m^{ −8} −21m^{ 2}$

3. $\frac { d } { d k } ( k ^ { 0 } )$

   Hint (c):

   Before differentiating, rewrite $k^{0}$ in a simpler form.

4. $\frac { d } { d t } ( ( 3 t ) ( 2 t + 5 ) )$

   Hint (d):

   Before differentiating, distribute.