- #1
pavadrin
- 156
- 0
Hey
Recently I have been given multiple problems to solve by means of integration. There are some problems which I am unsure on how to go about solving, or just don’t know. All help is greatly appreciated.
Find the indefinite integral of [tex]\int {xe^{x^2 } } \;dx[/tex]
This problem I simply do not know how to solve.
Find the indefinite integral of [tex]\int {\frac{7}{{x^2 + 4x + 12}}} \;dx[/tex]
This problem I began by trying to find factors of denominator of the fraction however found none. My reasoning on how to go about solving this problem is shown below, however I am unsure about my final answer.
[tex]
\begin{array}{l}
f\left( x \right) = \int {\frac{7}{{x^2 + 4x + 12}}} \;dx \\
\int {\frac{7}{{\left( {x + 2} \right)^2 + 8}}} \;dx \\
\int {\frac{7}{{u^2 + 8}}} \;dx\quad \quad u = x + 2 \\
u' = \frac{{du}}{{dx}} \\
dx = \frac{{du}}{{u'}} \\
dx = \frac{{du}}{1} \\
\int {\frac{7}{{u^2 + 8}}} \;du \\
7\int {\frac{1}{{u^2 + 8}}\,du} \\
f\left( x \right) = \ln \left| {u^2 + 8x} \right| + c \\
f\left( x \right) = \ln \left| {\left( {x + 2} \right)^2 + 8x} \right| + c \\
f\left( x \right) = \ln \left| {x^2 + 12x + 4} \right| + c \\
\end{array}
[/tex]
There are others, but I'll only post these for now. I'll go back and try the others again and I may not need to post them here. Thanks in advance again,
Pavadrin
Recently I have been given multiple problems to solve by means of integration. There are some problems which I am unsure on how to go about solving, or just don’t know. All help is greatly appreciated.
_______________________________
Find the indefinite integral of [tex]\int {xe^{x^2 } } \;dx[/tex]
This problem I simply do not know how to solve.
_______________________________
Find the indefinite integral of [tex]\int {\frac{7}{{x^2 + 4x + 12}}} \;dx[/tex]
This problem I began by trying to find factors of denominator of the fraction however found none. My reasoning on how to go about solving this problem is shown below, however I am unsure about my final answer.
[tex]
\begin{array}{l}
f\left( x \right) = \int {\frac{7}{{x^2 + 4x + 12}}} \;dx \\
\int {\frac{7}{{\left( {x + 2} \right)^2 + 8}}} \;dx \\
\int {\frac{7}{{u^2 + 8}}} \;dx\quad \quad u = x + 2 \\
u' = \frac{{du}}{{dx}} \\
dx = \frac{{du}}{{u'}} \\
dx = \frac{{du}}{1} \\
\int {\frac{7}{{u^2 + 8}}} \;du \\
7\int {\frac{1}{{u^2 + 8}}\,du} \\
f\left( x \right) = \ln \left| {u^2 + 8x} \right| + c \\
f\left( x \right) = \ln \left| {\left( {x + 2} \right)^2 + 8x} \right| + c \\
f\left( x \right) = \ln \left| {x^2 + 12x + 4} \right| + c \\
\end{array}
[/tex]
_______________________________
There are others, but I'll only post these for now. I'll go back and try the others again and I may not need to post them here. Thanks in advance again,
Pavadrin