Search any question & find its solution
Question:
Answered & Verified by Expert
Integrate the rational functions
$\frac{3 x-1}{(x-1)(x-2)(x-3)}$
$\frac{3 x-1}{(x-1)(x-2)(x-3)}$
Solution:
2282 Upvotes
Verified Answer
Let $\frac{3 x-1}{(x-1)(x-2)(x-3)}=\frac{A}{(x-1)}+\frac{B}{(x-2)}+\frac{C}{(x-3)}$
$\Rightarrow 3 \mathrm{x}-1$
$=\mathrm{A}(\mathrm{x}-2)(\mathrm{x}-3)+\mathrm{B}(\mathrm{x}-1)(\mathrm{x}-3)+\mathrm{C}(\mathrm{x}-1)(-2) \quad \ldots(i)$
Put $x=1,2,3$ in (i), we get : $\mathrm{A}=1, \mathrm{~B}=-5 \& \mathrm{C}=4$
$\begin{aligned}
&\therefore \mathrm{I}=\int \frac{1}{\mathrm{x}-1} \mathrm{dx}-5 \int \frac{1}{\mathrm{x}-2} \mathrm{dx}+4 \int \frac{1}{\mathrm{x}-3} \mathrm{dx} \\
&=\log |\mathrm{x}-1|-5 \log |\mathrm{x}-2|+4 \log |\mathrm{x}-3|+\mathrm{C}
\end{aligned}$
$\Rightarrow 3 \mathrm{x}-1$
$=\mathrm{A}(\mathrm{x}-2)(\mathrm{x}-3)+\mathrm{B}(\mathrm{x}-1)(\mathrm{x}-3)+\mathrm{C}(\mathrm{x}-1)(-2) \quad \ldots(i)$
Put $x=1,2,3$ in (i), we get : $\mathrm{A}=1, \mathrm{~B}=-5 \& \mathrm{C}=4$
$\begin{aligned}
&\therefore \mathrm{I}=\int \frac{1}{\mathrm{x}-1} \mathrm{dx}-5 \int \frac{1}{\mathrm{x}-2} \mathrm{dx}+4 \int \frac{1}{\mathrm{x}-3} \mathrm{dx} \\
&=\log |\mathrm{x}-1|-5 \log |\mathrm{x}-2|+4 \log |\mathrm{x}-3|+\mathrm{C}
\end{aligned}$
Looking for more such questions to practice?
Download the MARKS App - The ultimate prep app for IIT JEE & NEET with chapter-wise PYQs, revision notes, formula sheets, custom tests & much more.