由y=f*g（f,g是两个函数）的导数公式可知：
y=f'*g+f*g'
又由f(g)'=f'*g'
所以y'=(2x)'*sin(2x+5)+2x*[sin(2x+5)]'
=2sin(2x+5)+2xcos(2x+5)*2
=2sin(2x+5)+4xcos(2x+5)