Partial Fractions

IloveManUtd

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Joined
Jul 27, 2010
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I've got a question that asks me to express [5x+9/(x+3)^2] as partial fractions. I do not know how to express the denominator. Please help. Thx
 
The set-up is: (5x + 9)/(x + 3)^2 = A/(x +3) + B/(x + 3)^2

On the right-hand side, get a common denominator, and combine the ratios.

Equating numerators on each side then leads to:

Ax + 3A + B = 5x + 9

Equating coefficients yields:

Ax = 5x

and

3A + B = 9

Solve this system, to find A and B.
 
\(\displaystyle IloveManUtd, \ once \ you \ learn \ the \ system, \ to \ avoid \ all \ the \ grunt \ work,\)

\(\displaystyle (if \ you \ have \ a \ trusty \ TI-89) \ then \ do \ this:\)

\(\displaystyle F2,3,[(5x+9)/(x+3)^2,x] \ = \ \frac{5}{x+3}-\frac{6}{(x+3)^2}\)
 
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