- #1
b0rsuk
- 5
- 0
Homework Statement
Hello. I have a problem with a innocent-looking integral:
[tex] \int\frac{x^2 + 7x + 12}{x + 4} dx [/tex]
It doesn't look like i can use the law of sines, because the numerator is of higher order than the denominator. It doesn't look like the numerator is a multiple of the denominator or vice versa. It doesn't look like I can split the relatively complex numerator to an useful product.
It looks like it relies on some high school level math for solving polynomials / fractions, but my math is rather rusty in some places and I can't seem to recall anything. I could look for the method if I knew its name. Sometimes it's best to ask a human being.
Homework Equations
It's from introductory examples, which means I'm not yet allowed to use:
- Integration by substitution
- Integration by parts
The Attempt at a Solution
[tex]\int\frac{x^2 + 7x + 12}{x + 4} dx = \int \frac{x^2}{x + 4} + \frac{7x}{x + 4} + \frac{12}{x + 4} dx =[/tex]
[tex]=\int \frac{x^2}{x + 4} + \frac{7x}{x + 4}dx + 12 \int \frac{dx}{x + 4} =[/tex]
[tex]= \int \frac{x^2}{x + 4} + \frac{7x}{x + 4}dx + 12 \ln |x + 4| + C_1[/tex]
No, I can't get very far.