Partial Fractions: Solving Numerator Issues

In summary, the numerator of the first fraction should have a constant term, while the numerator of the second fraction should have a linear term. This ensures that the partial fractions can be added back up to the original fraction.
  • #1
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I'm having trouble understanding what the numerator needs to be in the partial fractions.
e.g.

[tex]\frac{1}{(x-1)(x-2)^2}\equiv \frac{A}{x-1}+\frac{Bx+C}{(x-2)^2}[/tex]

Notice how the first numerator has a constant A, while the second is linear Bx+C.
Actually... just now I think I may understand it. Does it have to do with the fact that during synthetic division, the remainder is always 1 degree less than the divisor? The second fraction's denominator is a quadratic, so its numerator should be linear?
 
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  • #2
"Does it have to do with the fact that during synthetic division, the remainder is always 1 degree less than the divisor? The second fraction's denominator is a quadratic, so its numerator should be linear?"

Essentially - the numerator should always be the "most general" polynomial of lower degree than the denominator
 

FAQ: Partial Fractions: Solving Numerator Issues

What are partial fractions?

Partial fractions are a method used in algebra to break down a complex fraction into smaller, simpler fractions. This is useful for solving equations and evaluating integrals.

How do you solve for the numerator in a partial fraction?

To solve for the numerator in a partial fraction, you first need to factor the denominator. Then, set up a system of equations using the coefficients of each term in the numerator and solve for the unknown variables. Finally, substitute these values back into the original fraction to get the simplified form.

Can all fractions be written as partial fractions?

No, not all fractions can be written as partial fractions. The fraction must be a rational function, meaning that the numerator and denominator are both polynomials. If the fraction contains any other types of expressions, such as radicals or logarithms, it cannot be written as partial fractions.

Why do we use partial fractions in mathematics?

We use partial fractions in mathematics to simplify complex fractions, solve equations, and evaluate integrals. It allows us to break down a complicated expression into smaller, more manageable parts, making it easier to work with and solve.

Are there any special cases to consider when solving for the numerator in partial fractions?

Yes, there are a few special cases to consider when solving for the numerator in partial fractions. These include repeated linear factors, irreducible quadratic factors, and repeated irreducible quadratic factors. Each case requires a slightly different approach to solve for the unknown variables in the numerator.

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