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How would i do the following indefinite integration $\int \frac{1}{x^2+10x+21} \, dx$

so far I've turned the bottom polynomial into $(x+7)(x+3)$ not too sure where to go from here

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Hint: Partial Fractions: $\frac{1}{(x+7)(x+3)}=\frac{A}{x+7}+\frac{B}{x+3}$ Now find $A,B$ and use the linearity of the integral: $\int \frac{1}{(x+7)(x+3)} dx=\int \frac{A}{x+7}dx+\int \frac{B}{x+3}dx$ This should be simple now.

EDIT: Evaluating $A,B$: $\frac{1}{(x+7)(x+3)}=\frac{A}{x+7}+\frac{B}{x+3}\iff 1=A(x+3)+B(x+7)$ Setting $x=-3$ and $x=-7$ give $A,B=?$

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    @jill Exactly!!2012-12-22