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# Cannot do this partial fractions question! watch

1. So I have this fraction to write in partials:

(x+1) / (x+3)^2

and I've rewritten it, equated the numerators, etc to get x+1=A(x+3)^2 + B(x+3)

Now I'm stuck, because I can't substitute -3 in as that will get rid of both A and B, and I can't expand and equate coefficients of x^2 and x, as I get A=0

Completely stuck, how can I get to the answer?

2. Substitute, say, x=-2 and x=-1 instead. You'll get two simultaneous equations in A and B.

Alternatively, you don't even need to do it this way. You can write x+1 = (x+3) - 2, and split the fraction that way.
3. Thanks! I tried the first thing you said before but must have done it wrong, cheers for the help

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Updated: April 10, 2011
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