Math Problem Statement

Rewrite the expression f(x) = (4x - 3) / (x^2(x - 2)) using partial fractions.

Solution

To rewrite the given function using partial fractions, we need to express the rational function in a form where it is broken down into simpler fractions. The function given is:

f(x)=4x3x2(x2)f(x) = \frac{4x - 3}{x^2(x - 2)}

Step 1: Set up the partial fraction decomposition.

We will decompose the expression into terms based on the factors in the denominator: x2(x2)x^2(x - 2). The general form of the partial fraction decomposition is:

4x3x2(x2)=Ax+Bx2+Cx2\frac{4x - 3}{x^2(x - 2)} = \frac{A}{x} + \frac{B}{x^2} + \frac{C}{x - 2}

Here, AA, BB, and CC are constants we need to determine.

Step 2: Combine the right-hand side over a common denominator.

To do that, express the terms on the right-hand side with the common denominator x2(x2)x^2(x - 2):

Ax+Bx2+Cx2=A(x)(x2)+B(x2)+C(x2)x2(x2)\frac{A}{x} + \frac{B}{x^2} + \frac{C}{x - 2} = \frac{A(x)(x - 2) + B(x - 2) + C(x^2)}{x^2(x - 2)}

Now we can simplify the numerator on the right-hand side:

A(x)(x2)=A(x22x)A(x)(x - 2) = A(x^2 - 2x) B(x2)=Bx2BB(x - 2) = Bx - 2B C(x2)=Cx2C(x^2) = Cx^2

So the expression becomes:

A(x22x)+B(x2)+Cx2=(A+C)x2+(B2A)x2BA(x^2 - 2x) + B(x - 2) + Cx^2 = (A + C)x^2 + (B - 2A)x - 2B

Step 3: Equate the numerators.

Now, equate the numerator of this expression to the numerator of the original fraction 4x34x - 3:

(A+C)x2+(B2A)x2B=4x3(A + C)x^2 + (B - 2A)x - 2B = 4x - 3

Step 4: Solve for AA, BB, and CC.

By comparing the coefficients of powers of xx, we get the following system of equations:

  1. A+C=0A + C = 0 (coefficient of x2x^2),
  2. B2A=4B - 2A = 4 (coefficient of xx),
  3. 2B=3-2B = -3 (constant term).

From the third equation, we can solve for BB:

2B=3B=32-2B = -3 \quad \Rightarrow \quad B = \frac{3}{2}

Now substitute B=32B = \frac{3}{2} into the second equation:

322A=42A=432=8232=52\frac{3}{2} - 2A = 4 \quad \Rightarrow \quad -2A = 4 - \frac{3}{2} = \frac{8}{2} - \frac{3}{2} = \frac{5}{2}

A=54A = -\frac{5}{4}

Finally, use A+C=0A + C = 0 to find CC:

54+C=0C=54-\frac{5}{4} + C = 0 \quad \Rightarrow \quad C = \frac{5}{4}

Step 5: Write the final partial fraction decomposition.

Substitute the values of AA, BB, and CC into the partial fraction decomposition:

4x3x2(x2)=54x+32x2+54x2\frac{4x - 3}{x^2(x - 2)} = \frac{-\frac{5}{4}}{x} + \frac{\frac{3}{2}}{x^2} + \frac{\frac{5}{4}}{x - 2}

This is the partial fraction decomposition of the given function.


Would you like any further details or explanations?

Relative Questions:

  1. How would the decomposition change if the denominator had complex roots?
  2. Can we apply the same method for higher-order factors in the denominator, such as x3x^3?
  3. What are the conditions under which partial fraction decomposition can be applied?
  4. Can partial fractions be used in integral calculus? If so, how?
  5. How would the procedure change if the numerator was of higher degree than the denominator?

Tip:

When performing partial fraction decomposition, always check if the degree of the numerator is lower than the degree of the denominator. If not, perform polynomial long division first.

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Math Problem Analysis

Mathematical Concepts

Partial Fractions
Rational Functions
Algebra

Formulas

f(x) = (4x - 3) / (x^2(x - 2))
Partial fraction decomposition: (A/x) + (B/x^2) + (C/(x - 2))

Theorems

Partial Fraction Decomposition Theorem

Suitable Grade Level

Grades 11-12