How Do You Integrate \(\int \frac{x-3}{x^2+2x-5}dx\) with Complex Roots?

Tasy
Messages
1
Reaction score
0
\int \frac{x-3}{x^2+2x-5}dx

How integrate this task?

x^2+2x-5=0

D=24, so I can't get real root.
 
Physics news on Phys.org
Tasy said:
\int \frac{x-3}{x^2+2x-5}dx

How integrate this task?

x^2+2x-5=0

D=24, so I can't get real root.

OK, that line with the discriminant made no sense. The discriminant is greater than zero, so clearly the quadratic does have real, distinct roots.

Hint: start off with completing the square on the denominator. In other words, express the denominator in the form (x+a)^2 + c and go from there.
 
Last edited:
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
Back
Top