00:01
In this problem we are provided with the thermic effect of food which is given by f of t which equals to negative 11 .42 plus 174 .3 times t times e raised to the power negative t over 1 .1 where the unit is kilojoules per hour and the time t is in r's.
00:33
We are asked to find out the total thermic energy for five hours, that is, from time t equals to zero up to time t equals to five.
00:45
So let us denote this total thermic energy as t.
00:49
So we have t to be equal to integral zero to five f of t which is negative 11 .4 .4 plus 174 .3 times t, times e raised to the power negative t over 1 .1 dt.
01:06
So in order to evaluate this, we make use of the property and write down the integral as negative 11 .42 times integral 0 to 5 d t plus 174 .3 times integral 0 to 5 t times e raised to the power negative t over 1 .1 d t.
01:30
So we begin by evaluating the second integral by integration by parts integral u dv equals to uv minus integral v d u.
01:41
Here we consider u to be equal to t and we consider v to be equal to sorry we consider dv to be equal to e raised to the power negative t over 1 .1.
01:53
So now differentiating u we have d u to be equal to d t and integrating dv we have v equals to e raised to the power negative t over 1 .1 times negative 1 .1.
02:07
So now substituting this in the formula of integration byparts we have integral t times e raised to the power negative t over 1 .1 d t to be equal to u times v which is negative 1 .1 times t times e raised to the power negative t over 1 .1 minus integral negative 1 .1 times e raised to the power negative t over 1 .1 d t.
02:37
So this can be written as negative 1 .1 t e raised to the power negative t over 1 .1 plus 1 .1 times integral of e raised to the power negative t over 1 .1 d t.
02:55
So evaluating the integral we obtain the value of of the integral to be equal to negative 1 .1 times e raised to the power negative t over 1 .1.
03:12
So this can be further simplified and written as negative 1 .1 times e raised to the power negative t over 1 .1 times t plus 1 .1...