Given integral
We need to evaluate
I = ∫ ( 1 x + 1 x 3 ) ( 3 x − 24 + x − 26 23 ) d x . I=\int \left(\frac1x+\frac1{x^3}\right)\left(\sqrt[23]{3x^{-24}+x^{-26}}\right)\,dx. I = ∫ ( x 1 + x 3 1 ) ( 23 3 x − 24 + x − 26 ) d x .
Since
3 x − 24 + x − 26 23 = ( 3 x − 24 + x − 26 ) 1 / 23 , \sqrt[23]{3x^{-24}+x^{-26}}=(3x^{-24}+x^{-26})^{1/23}, 23 3 x − 24 + x − 26 = ( 3 x − 24 + x − 26 ) 1/23 ,
we rewrite:
I = ∫ ( 1 x + 1 x 3 ) ( 3 x − 24 + x − 26 ) 1 / 23 d x . I=\int \left(\frac1x+\frac1{x^3}\right)(3x^{-24}+x^{-26})^{1/23}\,dx. I = ∫ ( x 1 + x 3 1 ) ( 3 x − 24 + x − 26 ) 1/23 d x .
Look for substitution
Notice
3 x − 24 + x − 26 3x^{-24}+x^{-26} 3 x − 24 + x − 26
has derivative
d d x ( 3 x − 24 + x − 26 ) = − 72 x − 25 − 26 x − 27 . \frac{d}{dx}(3x^{-24}+x^{-26})=-72x^{-25}-26x^{-27}. d x d ( 3 x − 24 + x − 26 ) = − 72 x − 25 − 26 x − 27 .
Factor this:
− 72 x − 25 − 26 x − 27 = − 2 ( 36 x − 25 + 13 x − 27 ) . -72x^{-25}-26x^{-27}=-2\left(36x^{-25}+13x^{-27}\right). − 72 x − 25 − 26 x − 27 = − 2 ( 36 x − 25 + 13 x − 27 ) .
That does not directly match the factor ( 1 x + 1 x 3 ) \left(\frac1x+\frac1{x^3}\right) ( x 1 + x 3 1 ) , so let us instead inspect the answer form.
We are given that
I = − α 3 ( α + 1 ) ( 3 x β + x γ ) α + 1 α + C . I=-\frac{\alpha}{3(\alpha+1)}\left(3x^\beta+x^\gamma\right)^{\frac{\alpha+1}{\alpha}}+C. I = − 3 ( α + 1 ) α ( 3 x β + x γ ) α α + 1 + C .
This suggests the integrand is of the form
( 3 x β + x γ ) 1 / α ⋅ d d x ( 3 x β + x γ ) . (3x^\beta+x^\gamma)^{1/\alpha}\cdot \frac{d}{dx}(3x^\beta+x^\gamma). ( 3 x β + x γ ) 1/ α ⋅ d x d ( 3 x β + x γ ) .
Match the inner expression
The given integrand contains
( 3 x − 24 + x − 26 ) 1 / 23 . (3x^{-24}+x^{-26})^{1/23}. ( 3 x − 24 + x − 26 ) 1/23 .
So naturally we identify
α = 23 , \alpha=23, α = 23 ,
and
β = − 24 , γ = − 26. \beta=-24,\qquad \gamma=-26. β = − 24 , γ = − 26.
Now verify whether the outside factor matches the derivative pattern.
Let
u = 3 x − 24 + x − 26 . u=3x^{-24}+x^{-26}. u = 3 x − 24 + x − 26 .
Then
d ν d x = − 72 x − 25 − 26 x − 27 = − 2 x − 27 ( 36 x 2 + 13 ) . \frac{d\nu}{dx}=-72x^{-25}-26x^{-27}=-2x^{-27}(36x^2+13). d x d ν = − 72 x − 25 − 26 x − 27 = − 2 x − 27 ( 36 x 2 + 13 ) .
But the factor in the integrand is
1 x + 1 x 3 = x − 1 + x − 3 = x − 3 ( x 2 + 1 ) . \frac1x+\frac1{x^3}=x^{-1}+x^{-3}=x^{-3}(x^2+1). x 1 + x 3 1 = x − 1 + x − 3 = x − 3 ( x 2 + 1 ) .
So direct substitution in u = 3 x − 24 + x − 26 u=3x^{-24}+x^{-26} u = 3 x − 24 + x − 26 does not fit immediately.
Try factoring the inner expression
Observe:
3 x − 24 + x − 26 = x − 26 ( 3 x 2 + 1 ) . 3x^{-24}+x^{-26}=x^{-26}(3x^2+1). 3 x − 24 + x − 26 = x − 26 ( 3 x 2 + 1 ) .
Hence
( 3 x − 24 + x − 26 ) 1 / 23 = x − 26 / 23 ( 3 x 2 + 1 ) 1 / 23 . (3x^{-24}+x^{-26})^{1/23}=x^{-26/23}(3x^2+1)^{1/23}. ( 3 x − 24 + x − 26 ) 1/23 = x − 26/23 ( 3 x 2 + 1 ) 1/23 .
Therefore the integrand becomes
( x − 1 + x − 3 ) x − 26 / 23 ( 3 x 2 + 1 ) 1 / 23 . \left(x^{-1}+x^{-3}\right)x^{-26/23}(3x^2+1)^{1/23}. ( x − 1 + x − 3 ) x − 26/23 ( 3 x 2 + 1 ) 1/23 .
This is not especially helpful directly.
So instead let us differentiate the given answer form and compare.
Differentiate the proposed antiderivative form
Suppose
I = − α 3 ( α + 1 ) ( 3 x β + x γ ) α + 1 α + C . I=-\frac{\alpha}{3(\alpha+1)}(3x^\beta+x^\gamma)^{\frac{\alpha+1}{\alpha}}+C. I = − 3 ( α + 1 ) α ( 3 x β + x γ ) α α + 1 + C .
Differentiating,
I ′ = − α 3 ( α + 1 ) ⋅ α + 1 α ( 3 x β + x γ ) 1 / α ( 3 β x β − 1 + γ x γ − 1 ) . I'= -\frac{\alpha}{3(\alpha+1)}\cdot \frac{\alpha+1}{\alpha}(3x^\beta+x^\gamma)^{1/\alpha}(3\beta x^{\beta-1}+\gamma x^{\gamma-1}). I ′ = − 3 ( α + 1 ) α ⋅ α α + 1 ( 3 x β + x γ ) 1/ α ( 3 β x β − 1 + γ x γ − 1 ) .
So
I ′ = − 1 3 ( 3 x β + x γ ) 1 / α ( 3 β x β − 1 + γ x γ − 1 ) . I'=-\frac13 (3x^\beta+x^\gamma)^{1/\alpha}(3\beta x^{\beta-1}+\gamma x^{\gamma-1}). I ′ = − 3 1 ( 3 x β + x γ ) 1/ α ( 3 β x β − 1 + γ x γ − 1 ) .
This must equal
( 1 x + 1 x 3 ) ( 3 x − 24 + x − 26 ) 1 / 23 . \left(\frac1x+\frac1{x^3}\right)(3x^{-24}+x^{-26})^{1/23}. ( x 1 + x 3 1 ) ( 3 x − 24 + x − 26 ) 1/23 .
Thus we must have
α = 23 , \alpha=23, α = 23 ,
and
3 x β + x γ = 3 x − 24 + x − 26 . 3x^\beta+x^\gamma=3x^{-24}+x^{-26}. 3 x β + x γ = 3 x − 24 + x − 26 .
Hence
β = − 24 , γ = − 26. \beta=-24,\qquad \gamma=-26. β = − 24 , γ = − 26.
Then
3 β x β − 1 + γ x γ − 1 = 3 ( − 24 ) x − 25 + ( − 26 ) x − 27 = − 72 x − 25 − 26 x − 27 . 3\beta x^{\beta-1}+\gamma x^{\gamma-1}=3(-24)x^{-25}+(-26)x^{-27}=-72x^{-25}-26x^{-27}. 3 β x β − 1 + γ x γ − 1 = 3 ( − 24 ) x − 25 + ( − 26 ) x − 27 = − 72 x − 25 − 26 x − 27 .
Therefore
I ′ = − 1 3 ( 3 x − 24 + x − 26 ) 1 / 23 ( − 72 x − 25 − 26 x − 27 ) . I'=-\frac13(3x^{-24}+x^{-26})^{1/23}(-72x^{-25}-26x^{-27}). I ′ = − 3 1 ( 3 x − 24 + x − 26 ) 1/23 ( − 72 x − 25 − 26 x − 27 ) .
I ′ = ( 3 x − 24 + x − 26 ) 1 / 23 ( 24 x − 25 + 26 3 x − 27 ) . I'=(3x^{-24}+x^{-26})^{1/23}\left(24x^{-25}+\frac{26}{3}x^{-27}\right). I ′ = ( 3 x − 24 + x − 26 ) 1/23 ( 24 x − 25 + 3 26 x − 27 ) .
This does not match the integrand exactly as typed.
So there is likely a typo in the printed coefficient form, but the intended identification from the structure is clearly
α = 23 , β = − 24 , γ = − 26. \alpha=23,\quad \beta=-24,\quad \gamma=-26. α = 23 , β = − 24 , γ = − 26.
Compute the required sum
α + β + γ = 23 − 24 − 26 = − 27. \alpha+\beta+\gamma=23-24-26=-27. α + β + γ = 23 − 24 − 26 = − 27.
Compare with stored answer
Stored correct answer is 19 19 19 , but the expression given in the question leads to
− 27 . \boxed{-27}. − 27 .
So I do not agree with the stored answer.
The most plausible issue is a typo in the question statement or answer key.