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Indefinite Integral - Evaluate Please.?

Evaluate the indefinite integral

((2/x^4)+(4/15x))dx.

The answer is not -2/(3 x^3)+(4ln(x))/15

1 Answer

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  • 9 years ago
    Favourite answer

    Hello,

    ∫ {(2 /x⁴) + [4 /(15x)]} dx =

    let's rewrite the integral as:

    ∫ [2x^(- 4) + (4 /15)(1 /x)] dx =

    let's split into two integrals pulling constants out:

    2 ∫ x^(- 4) dx + (4 /15) ∫ (1 /x) dx =

    2 [1/(- 4+1)] x^(- 4+1) + (4/15) ln | x | + C =

    2 [1/(- 3)] x^(- 3) + (4/15) ln | x | + C =

    - [2 /(3x³)] + (4/15) ln | x | + C

    the answer is - [2 /(3x³)] + (4/15) ln | x | + C (why not?)

    I hope it helps

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