Math Problem Statement

Find the values of the constants A and B such that p(x) = A / (x + 2) + B / (x + 2)^2, where p(x) = 2x / (x + 2)^2.

Solution

We are given the function p(x)=2x(x+2)2,x2p(x) = \frac{2x}{(x + 2)^2}, x \neq -2, and we are tasked to express it as a sum of two terms of the form Ax+2+B(x+2)2\frac{A}{x + 2} + \frac{B}{(x + 2)^2}, and then find the constants AA and BB.

Step 1: Set up the equation

We want to match the given expression with:

p(x)=Ax+2+B(x+2)2.p(x) = \frac{A}{x + 2} + \frac{B}{(x + 2)^2}.

Start by rewriting the right-hand side with a common denominator:

Ax+2+B(x+2)2=A(x+2)+B(x+2)2.\frac{A}{x + 2} + \frac{B}{(x + 2)^2} = \frac{A(x + 2) + B}{(x + 2)^2}.

Now, equate this to the given expression for p(x)p(x):

A(x+2)+B(x+2)2=2x(x+2)2.\frac{A(x + 2) + B}{(x + 2)^2} = \frac{2x}{(x + 2)^2}.

Step 2: Compare numerators

Since the denominators are the same, we can equate the numerators:

A(x+2)+B=2x.A(x + 2) + B = 2x.

Step 3: Expand and group terms

Now expand the left-hand side:

A(x+2)+B=Ax+2A+B.A(x + 2) + B = Ax + 2A + B.

This gives us:

Ax+2A+B=2x.Ax + 2A + B = 2x.

Step 4: Compare coefficients

Now, compare the coefficients of xx and the constant terms on both sides of the equation:

  • Coefficient of xx: A=2A = 2,
  • Constant term: 2A+B=02A + B = 0.

Step 5: Solve for AA and BB

We already have A=2A = 2. Substitute A=2A = 2 into the second equation:

2(2)+B=0    4+B=0    B=4.2(2) + B = 0 \implies 4 + B = 0 \implies B = -4.

Final Answer:

The values of AA and BB are:

A=2,B=4.A = 2, \quad B = -4.

Would you like more details, or do you have any other questions?

Related Questions:

  1. How can we check if the values of AA and BB are correct?
  2. What method can we use for partial fraction decomposition for higher-order polynomials?
  3. Can this technique be used for improper rational functions?
  4. How would you handle a situation where the denominator is not factored easily?
  5. How does this process change if the power of (x+2)(x + 2) in the denominator was higher than 2?

Tip: Always expand and simplify both sides of the equation when working with partial fractions to ensure the terms align correctly.

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Math Problem Analysis

Mathematical Concepts

Algebra
Partial Fraction Decomposition

Formulas

p(x) = A / (x + 2) + B / (x + 2)^2
p(x) = 2x / (x + 2)^2

Theorems

Partial Fraction Decomposition Theorem

Suitable Grade Level

Grades 10-12