y=2x*sin(2x+5)
y'=(2x)'*sin(2x+5)+2x*(sin(2x+5))'
=2sin(2x+5)+2x*cos(2x+5)*(2x+5)'
=2sin(2x+5)+2x*cos(2x+5)*2
=2sin(2x+5)+4xcos(2x+5)
%by dynamic
%see also http://www.matlabsky.com
%contact me matlabsky@gmail.com
%2009.2.
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