Math Problem Statement

solve this partial fraction

Solve this partial fraction

Solution

The given image shows a partial fraction decomposition problem, and it appears to be:

s4(s+4)2(s1)=As+4+B(s+4)2+Cs1\frac{s - 4}{(s + 4)^2 (s - 1)} = \frac{A}{s + 4} + \frac{B}{(s + 4)^2} + \frac{C}{s - 1}

To solve this, we need to find the constants AA, BB, and CC.

Step-by-step Solution:

  1. Multiply both sides by the denominator (s+4)2(s1)(s + 4)^2(s - 1) to eliminate the fractions:

s4=A(s+4)(s1)+B(s1)+C(s+4)2s - 4 = A(s + 4)(s - 1) + B(s - 1) + C(s + 4)^2

  1. Expand both sides:

    • Expand A(s+4)(s1)A(s + 4)(s - 1): A(s+4)(s1)=A(s2s+4s4)=A(s2+3s4)A(s + 4)(s - 1) = A(s^2 - s + 4s - 4) = A(s^2 + 3s - 4)
    • Expand B(s1)B(s - 1): B(s1)=B(s1)B(s - 1) = B(s - 1)
    • Expand C(s+4)2C(s + 4)^2: C(s+4)2=C(s2+8s+16)C(s + 4)^2 = C(s^2 + 8s + 16)

    Now, the equation becomes: s4=A(s2+3s4)+B(s1)+C(s2+8s+16)s - 4 = A(s^2 + 3s - 4) + B(s - 1) + C(s^2 + 8s + 16)

  2. Group similar terms: s4=(A+C)s2+(3A+B+8C)s+(4AB+16C)s - 4 = (A + C)s^2 + (3A + B + 8C)s + (-4A - B + 16C)

  3. Compare coefficients: Now, we compare the coefficients of powers of ss on both sides of the equation:

    • For s2s^2: A+C=0A + C = 0
    • For ss: 3A+B+8C=13A + B + 8C = 1
    • Constant term: 4AB+16C=4-4A - B + 16C = -4
  4. Solve the system of equations:

    From A+C=0A + C = 0, we get: A=CA = -C

    Substitute A=CA = -C into the other two equations:

    For 3A+B+8C=13A + B + 8C = 1: 3(C)+B+8C=13C+B+8C=1B+5C=1B=15C3(-C) + B + 8C = 1 \quad \Rightarrow \quad -3C + B + 8C = 1 \quad \Rightarrow \quad B + 5C = 1 \quad \Rightarrow \quad B = 1 - 5C

    For 4AB+16C=4-4A - B + 16C = -4: 4(C)B+16C=44CB+16C=420CB=4-4(-C) - B + 16C = -4 \quad \Rightarrow \quad 4C - B + 16C = -4 \quad \Rightarrow \quad 20C - B = -4

    Substitute B=15CB = 1 - 5C into this equation: 20C(15C)=420C1+5C=425C=3C=32520C - (1 - 5C) = -4 \quad \Rightarrow \quad 20C - 1 + 5C = -4 \quad \Rightarrow \quad 25C = -3 \quad \Rightarrow \quad C = -\frac{3}{25}

  5. Find AA and BB:

    • Since A=CA = -C, we have: A=325A = \frac{3}{25}
    • Using B=15CB = 1 - 5C: B=15(325)=1+1525=1+35=85B = 1 - 5\left(-\frac{3}{25}\right) = 1 + \frac{15}{25} = 1 + \frac{3}{5} = \frac{8}{5}

Final Answer:

Thus, the partial fraction decomposition is: s4(s+4)2(s1)=325s+4+85(s+4)2+325s1\frac{s - 4}{(s + 4)^2 (s - 1)} = \frac{\frac{3}{25}}{s + 4} + \frac{\frac{8}{5}}{(s + 4)^2} + \frac{-\frac{3}{25}}{s - 1}

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Here are 5 related questions you might explore:

  1. How can you solve partial fractions with more than two terms in the denominator?
  2. What happens if the numerator is a quadratic term instead of linear?
  3. How do partial fractions help in solving integrals?
  4. Can partial fractions be applied to improper fractions, and how do you handle them?
  5. What is the significance of the degree of the denominator in determining the form of the partial fraction?

Tip: When solving partial fractions, always expand and match coefficients of each power of the variable to set up a system of equations efficiently.

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Math Problem Analysis

Mathematical Concepts

Partial Fractions
Rational Functions
Algebraic Decomposition

Formulas

Partial fraction decomposition
System of linear equations

Theorems

Partial Fraction Theorem
Decomposition of rational expressions

Suitable Grade Level

Grades 11-12