The expression `(2x)/(x^3+5x^2+2x-8)` has to be expressed as partial fractions.
First determine the factors of x^3+5x^2+2x-8
x^3+5x^2+2x-8
=> x^3 + 4x^2 + x^2 + 4x - 2x - 8
=> x^2(x + 4) + x(x + 4) - 2(x + 4)
=> (x^2 + x - 2)(x + 4)
=> (x^2 + 2x - x - 2)(x + 4)
=> (x(x + 2) - 1(x + 2))(x + 4
=> (x - 1)(x + 2)(x + 4)
`(2x)/(x^3+5x^2+2x-8)`
=> `(2x)/((x - 1)(x + 2)(x + 4))`
=> `A/(x - 1) + B/(x + 2) + C/(x + 4)`
=> `(A(x^2 + 6x + 8) + B(x^2 + 3x - 4) + C(x^2 + x - 2))/((x - 1)(x + 2)(x + 4))`
=> `x^2(A + B + C) + x(6A + 3B + C) + 8A - 4B - 2C = 2x`
=> `A + B + C = 0, 6A + 3B + C = 2 and 8A - 4B - 2C = 0`
Solve for A, B and C
A + B + C = 0 ...(1)
6A + 3B + C = 2 ...(2)
4A - 2B - C = 0 ...(3)
(1) + (3)
=> 5A - B = 0
=> B = 5A
From (1), C = -A - B = -A - 5A
Substitute in (2)
=> 6A + 15A -6A = 2
=> 15A = 2
=> A = `2/15`
B = `2/3`
C = `-4/5`
The partial fraction expansion of ` ``(2x)/(x^3+5x^2+2x-8)` is `2/(15*(x - 1)) + 2/(3*(x+2)) - 4/(5*(x + 4))`
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