00:01
So this is the problem 2 of chapter 8 .3.
00:04
And we have integral from 0 to pi 3 times sine of x over 3x.
00:17
Now, if you can tell directly the antiterate of this integral that is excellent, but if you do not, that's fine.
00:27
The systematic approach to this is, well, let's change.
00:34
The it's changed the substitution x over 3 is equal to u then we would have sign of u here who is the antedriety we know to be negative cosine right so if you if you do this we will have well d u is equal to derivative of x over 3 which is 1 3 times d x and then the bound for u is since x is going from 0 to pi, the bound for u would be 0 all the way up to pi over 3.
01:12
So then we have now our integral in terms of u with the new boundaries.
01:20
And i have 3 here and sign u.
01:27
And then dx will become 3 will become 3 times d u.
01:37
I will have 3 times the u...