00:01
The integral test for series allows us to determine whether a series diverges or converges by evaluating the integral from 1 to infinity of the sequence.
00:13
So we have an and dn.
00:18
In this problem, we're given, once again we're going to evaluate this, with an in our problem is given to be equal to 1 over 4 3n minus 1 to the power of 3.
00:35
So we have then 1 to infinity.
00:39
So we just keep the variable n instead of replacing it with other variables.
00:44
1 over 4 3n minus 1 cubed dn.
00:49
So we're gonna apply here the u substitution.
00:54
We get that let us take u as 3n minus 1 then therefore take the derivative of this du we have 3dn.
01:04
Take divide both sides by 3, you get du over 3 equals dn.
01:10
So we have then note that we can take out the 4 here as 1 4th and then 1 to infinity 1 over 3n minus 1 cubed dn.
01:21
So if i apply the the new variable we just keep from writing the limits.
01:30
We just apply them later as we bring back the original variable...