[填空题]
The concentration in mg of a certain medicine t hours aftp 1k7i1.qx.s ushjep6er adm;w8 hjv,aeuj *inistration can be modeled by C(t) =u; ,vhaj e8jw* 1000te$^{-1.25t}$ , t≥0.
1.Find the rate of change of the concentration with respect to time.
C'(t) = 1000e$^{-1.25t}(a-b1.25t)$ , a= , b= .
2.Find the value of t when the rate of change of C is zero.
t= .
3.Determine if the time found in part (b) is a local minima or maxima for C. Justify your answer.
