Can't get integration right

[Marcio]

Hello all,

Would you be king enough as to point out what I am doing wrong with this very simple integration?

\[t = \int_0^{0.515}\frac{1}{0.000273\times exp\left[16306\times\left(\frac{1}{535}-\frac{1}{535+90.45x}\right)\right](1-x)} dx\]

The correct answer is \(833\) but I keep getting \(838.867\pm2.38E-7\) with FIX 9.

This is the code I am using on the 15C:

R0 = 0.000273
R1 = 16306
R2 = 535
R3 = 90.45

Code:

LBL 0
RCL 3
x
RCL 2
+
CHS
1/X
RCL 2
1/X
+
RCL 1
x
exp
RCL 0
x
x<>y
CHS
1
+
x
1/X
RTN

Very much appreciated.