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Math question....Integral?

What is the integral of this function....

(x^2 + 4x + 8) / (x + 1)

I know it uses U substitution but I can't figure it out.

8 Answers

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  • 9 years ago
    Favorite Answer

    Divide the polynomials by the comparing coefficients method:

    (x² + 4x + 8) / (x + 1) = Ax + B + C / (x + 1)

    x² + 4x + 8 = Ax(x + 1) + B(x + 1) + C

    x² + 4x + 8 = Ax² + Ax + Bx + B + C

    x² + 4x + 8 = Ax² + (A + B)x + (B + C)

    A = 1

    A + B = 4

    B = 4 - A

    B = 4 - 1

    B = 3

    B + C = 8

    C = 8 - B

    C = 8 - 3

    C = 5

    (x² + 4x + 8) / (x + 1) = x + 3 + 5 / (x + 1)

    Integrate the expression term by term using this result:

    ∫ (x² + 4x + 8) / (x + 1) dx = ∫ [x + 3 + 5 / (x + 1)] dx

    ∫ (x² + 4x + 8) / (x + 1) dx = ∫ x dx + 3 ∫ 1 dx + 5 ∫ 1 / (x + 1) dx

    ∫ (x² + 4x + 8) / (x + 1) dx = x² / 2 + 3x + 5ln|x + 1| + C

  • 9 years ago

    (x^2 + 4x + 8) / (x + 1) = x + 3 + [5 / (x + 1) ]

    The integration of this function is

    [(x^2) / 2] + 3x + 5 log|x + 1| + C

    Source(s): self knowdge
  • 9 years ago

    (x^2 + 4x + 8) / (x + 1)

    = (x^2 + x + 3x + 3 + 5) / (x + 1)

    = x + 3 + 5/(x+1)

    So, the integral = (1/2)x^2 + 3x + 5ln|x+1| + c

  • ??????
    Lv 7
    9 years ago

    We divide x²+4x+8 through x+1, this gives

    x+3 and 5/(x+1) as remainder

    so we integrate x+3 = x²/2+3x+C

    and 5/(x+1) = 5 ln( | 1+x | ) + C '

    so add both we have

    x²/2 + 3x + 5 ln (|1+x|) + C"

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  • u = x + 1

    du = dx

    x = u - 1

    (x^2 + 4x + 8) * dx / (x + 1) =>

    ((u - 1)^2 + 4 * (u - 1) + 8) * du / u =>

    (u^2 - 2u + 1 + 4u - 4 + 8) * du / u =>

    (u^2 + 2u + 5) * du / u =>

    u * du + 2 * du + 5 * du/u

    Integrate:

    (1/2) * u^2 + 2u + 5 * ln|u| + C =>

    (1/2) * (x + 1)^2 + 2 * (x + 1) + 5 * ln|x + 1| + C =>

    (1/2) * (x^2 + 2x + 1) + 2x + 2 + 5 * ln|x + 1| + C =>

    (1/2) * x^2 + x + (1/2) + 2x + 2 + 5 * ln|x + 1| + C =>

    (1/2) * x^2 + 3x + 5 * ln|x + 1| + (5/2) + C =>

    (1/2) * x^2 + 3x + 5 * ln|x + 1| + C =>

    (1/2) * (x^2 + 6x + 10 * ln|x + 1|) + C

  • 9 years ago

    ∫(x² + 4x + 8)/(x + 1) dx

    ∫((x + 2)² + 4)/(x + 1) dx

    ∫((x + 1)² + 2(x + 1) + 5)/(x + 1) dx

    ∫(x + 1) dx + ∫2 dx + ∫5/(x + 1) dx

    = x²/2 + 3x + 5*ln|x + 1| + C

  • ?
    Lv 4
    4 years ago

    Eh... neither... yet i guess i will choose English. I used to love English extra yet extreme college made it boring. -_- yet I nevertheless love writing as a interest (and hate math, even inspite of the actuality that i'm no longer undesirable at it) so i will purely say English.

  • divide the equation first. then you get x+3 + 5/x+1, then take the integral.

    I got x²/2 + 3x + 5ln |x+1| +c.

    if u have any questions feel free to ask :)

    Source(s): ma cute lil brain
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