本题计算过程如下：y=x^2sin(1/x)dy/dx=2xsin(1/x)+x^2cos(1/x)*(-1/x^2)=2xsin(1/x)-cos(1/x).
y = x^2 sin(1/x)dy/dx = (x^2)' sin(1/x) + x^2 [sin(1/x)]'= 2x sin(1/x) + x^2 cos(1/x) (- 1/x^2)= 2x sin(1/x) - cos(1/x)
