SOLUTION: Differentiate with respect to x, a) {{{y=(2x)/(e^x)}}} b) {{{y=3x*sin2x}}}

a) 

Write with constant coefficient  outside
   

Write denominator as a factor of numerator with negative
exponent:

   

Use product rules for derivative 
and 

of the inside of parentheses:

     
    
factor out 
   
   
Write  in the numerator as  in the denominator
   

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b) 

Write with constant coefficient  outside

   

Use product rule for derivative 
and 

of the inside of parentheses:

   

  

Edwin