Mathematica:Please help me to solve numerical integration

[shafieza_garl]

i have problem regarding to the numerical method. my problem is from da attachment,if i replace x with value 1,it will get da answer by using NIntegrate.I want to know if i can get the value of t_minimum from the answer.thanks a lots.

 

[jackmell]

You mean the minimum of the integral value in terms of x? If so, then how about:

f[t_] := 0.25*
   ((-4037.89 + Exp[0.015*t]*(4044.44 - 
        66.6667*t))/Exp[0.015*t])^2
myint[(x_)?NumericQ] := NIntegrate[f[t], 
   {t, 0, x}]
Plot[myint[x], {x, 0, 2}]
FindMinimum[{Evaluate[myint[x]], 
   0.5 <= x <= 1.5}, {x, 1}]