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General antiderivative of a sum of power functions

Let h(x)=3x−2xh(x) = 3\sqrt{x} - \dfrac{2}{\sqrt{x}}.

Find the general antiderivative H(x)H(x) of h(x)h(x).

Hint

Rewrite each term using fractional exponents: x=x1/2\sqrt{x} = x^{1/2} and 1x=x−1/2\dfrac{1}{\sqrt{x}} = x^{-1/2}. Then apply the reverse power rule ∫xn dx=xn+1n+1+C\int x^n\,dx = \dfrac{x^{n+1}}{n+1} + C to each term separately, and don't forget the single overall +C+C.

Step-by-step solution

Rewrite h(x)=3x1/2−2x−1/2h(x) = 3x^{1/2} - 2x^{-1/2}. Apply the reverse power rule term by term: ∫3x1/2 dx=3⋅x3/23/2=2x3/2\int 3x^{1/2}\,dx = 3 \cdot \dfrac{x^{3/2}}{3/2} = 2x^{3/2}, and ∫−2x−1/2 dx=−2⋅x1/21/2=−4x1/2\int -2x^{-1/2}\,dx = -2 \cdot \dfrac{x^{1/2}}{1/2} = -4x^{1/2}.

Adding these results and including a single arbitrary constant gives the general antiderivative H(x)=2x3/2−4x1/2+CH(x) = 2x^{3/2} - 4x^{1/2} + C. You can check this by differentiating: H′(x)=2⋅32x1/2−4⋅12x−1/2=3x1/2−2x−1/2=h(x)H'(x) = 2\cdot\frac{3}{2}x^{1/2} - 4\cdot\frac{1}{2}x^{-1/2} = 3x^{1/2} - 2x^{-1/2} = h(x), confirming the answer.

Role of the arbitrary constant

Hint
Step-by-step solution

The answer is C. In the solution to part a, the general antiderivative was written as H(x) = 2x^{3/2} - 4x^{1/2} + C, where C denotes the arbitrary constant of integration. This constant accounts for the fact that any two antiderivatives of the same function differ only by a constant, since the derivative of a constant is zero.

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