Math Problem Statement

Express the integrand as a sum of partial fractions and evaluate the integrals. Integral StartFraction x plus 8 Over 2 x cubed minus 8 x EndFraction dx Question content area bottom Part 1 Rewrite the integrand as the sum of partial fractions. StartFraction x plus 8 Over 2 x cubed minus 8 x EndFraction equals    enter your response here

Solution

We are given the following integral:

x+82x38xdx\int \frac{x + 8}{2x^3 - 8x} \, dx

Step 1: Factor the denominator

First, we factor the denominator 2x38x2x^3 - 8x:

2x38x=2x(x24)=2x(x2)(x+2)2x^3 - 8x = 2x(x^2 - 4) = 2x(x - 2)(x + 2)

Thus, the integrand becomes:

x+82x(x2)(x+2)\frac{x + 8}{2x(x - 2)(x + 2)}

Step 2: Set up partial fractions

We express the rational function as a sum of partial fractions of the form:

x+82x(x2)(x+2)=Ax+Bx2+Cx+2\frac{x + 8}{2x(x - 2)(x + 2)} = \frac{A}{x} + \frac{B}{x - 2} + \frac{C}{x + 2}

Step 3: Clear the denominator

Multiply both sides of the equation by 2x(x2)(x+2)2x(x - 2)(x + 2) to eliminate the denominators:

x+8=A2(x2)(x+2)+B2x(x+2)+C2x(x2)x + 8 = A \cdot 2(x - 2)(x + 2) + B \cdot 2x(x + 2) + C \cdot 2x(x - 2)

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

Now, expand and collect like terms to find the values of AA, BB, and CC.

For x=0x = 0:

x+8=A2(2)(2)+B2(0)(2)+C2(0)(2)x + 8 = A \cdot 2(-2)(2) + B \cdot 2(0)(2) + C \cdot 2(0)(-2) 8=8A8 = -8A A=1A = -1

For x=2x = 2:

x+8=A2(0)(4)+B2(2)(4)+C2(2)(0)x + 8 = A \cdot 2(0)(4) + B \cdot 2(2)(4) + C \cdot 2(2)(0) 10=16B10 = 16B B=1016=58B = \frac{10}{16} = \frac{5}{8}

For x=2x = -2:

x+8=A2(4)(0)+B2(2)(0)+C2(2)(4)x + 8 = A \cdot 2(-4)(0) + B \cdot 2(-2)(0) + C \cdot 2(-2)(-4) 6=16C6 = 16C C=616=38C = \frac{6}{16} = \frac{3}{8}

Step 5: Write the partial fraction decomposition

Now that we have the values of AA, BB, and CC, we can express the integrand as:

x+82x(x2)(x+2)=1x+5/8x2+3/8x+2\frac{x + 8}{2x(x - 2)(x + 2)} = \frac{-1}{x} + \frac{5/8}{x - 2} + \frac{3/8}{x + 2}

Final Answer

The integral is now in the form of a sum of partial fractions:

1x+5/8x2+3/8x+2\frac{-1}{x} + \frac{5/8}{x - 2} + \frac{3/8}{x + 2}

Would you like to proceed with evaluating the integrals, or do you need further explanation on this part?

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Math Problem Analysis

Mathematical Concepts

Integration
Partial Fractions
Algebraic Factorization

Formulas

Partial fraction decomposition formula
Integration of 1/x

Theorems

Partial fractions decomposition theorem
Integration of rational functions

Suitable Grade Level

Grades 11-12