Monday, September 24, 2018

Single Variable Calculus, Chapter 5, 5.4, Section 5.4, Problem 32

Find the integrals $\displaystyle \int^9_1 \frac{3x-2}{\sqrt{x}} dx$

$
\begin{equation}
\begin{aligned}
\int\frac{3x-2}{\sqrt{x}} dx &= \int \left( \frac{3x}{\sqrt{x}} - \frac{2}{\sqrt{x}} \right) dx \\
\\
\int\frac{3x-2}{\sqrt{x}} dx &= \int \left( 3x^{\frac{1}{2}} - 2x^{\frac{-1}{2}} \right) dx \\
\\
\int\frac{3x-2}{\sqrt{x}} dx &= 3 \int x^{\frac{1}{2}} dx - 2 \int x^{\frac{-1}{2}} dx\\
\\
\int\frac{3x-2}{\sqrt{x}} dx &= 3 \left( \frac{x^{\frac{1}{2} +1 }}{\frac{1}{2} +1 } \right) - 2 \left( \frac{x^{\frac{-1}{2}+1}}{\frac{-1}{2}+1 } \right) + C\\
\\
\int\frac{3x-2}{\sqrt{x}} dx &= 2 x^{\frac{3}{2}} - 2 \left( 2x^{\frac{1}{2}} \right) + C\\
\\
\int\frac{3x-2}{\sqrt{x}} dx &= 2x^{\frac{3}{2}} - 4x^{\frac{1}{2}} + C\\
\\
\int^9_1 \frac{3x-2}{\sqrt{x}} dx &= 2(9)^{\frac{3}{2}} - 4 (9)^{\frac{1}{2}} + C- \left[ 2(1)^{\frac{3}{2}} - 4(1)^{\frac{1}{2}} + C \right]\\
\\
\int^9_1 \frac{3x-2}{\sqrt{x}} dx &= 2\left[(9)^{\frac{1}{2}} \right]^3 - 4 (3) +C - 2 + 4 -C \\
\\
\int^9_1 \frac{3x-2}{\sqrt{x}} dx &= 2(3)^3 - 12 + 2\\
\\
\int^9_1 \frac{3x-2}{\sqrt{x}} dx &= 54 - 12 + 2\\
\\
\int^9_1 \frac{3x-2}{\sqrt{x}} dx &= 44

\end{aligned}
\end{equation}
$

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