00:04
Okay, to evaluate this integral, we have to first do the partial fraction decomposition of our 7x minus 2 over the 3x squared minus 2x.
00:16
Hopefully the first thing you notice is the way the denominator factors.
00:20
We can factor an x out of both of those, and so one of the factors is x.
00:25
The other factor is 3x minus 2.
00:28
So those would be the denominators in our partial fraction decomposition.
00:33
So we'll have a over x plus b over the 3x minus 2.
00:39
Now we multiply everything by the common denominator so that we can set up our system of equations to find a and b.
00:47
So multiplying gets rid of the fraction on the left -hand side.
00:51
We just have 7x minus 2.
00:54
Multiplying the right -hand side, each factor will reduce out.
00:58
So we have the numerator times the opposing factor in the other denominator.
01:05
So a times the 3x minus 2 is 3ax minus 2a, and then b times the x is plus bx.
01:16
And now we can equate our terms with each other and equate the coefficients.
01:23
So 7 is going to equal 3a plus b from the x terms, and then the negative 2 has to equal negative 2a from the constant terms.
01:37
Terms.
01:39
So a has to be 1, and then that means that b has to be 4.
01:45
So now we can rewrite our integral as the partial fraction decomposition of 1 over x plus 4 over 3x minus 2 dx, and that integral being evaluated from 1 to 2...