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 #1
avatar+26387 
+5
08.12.2014
 #2
avatar+26387 
+5

how to check that 2814749767109 and 59482661568307 are relatively prime

GCD(59482661568307, 2814749767109 ) with Euclidean algorithm:

 

 

$$\frac{59482661568307 }{2814749767109}
= \frac{59482661568307 -21*2814749767109}{2814749767109}
= \frac{372916459018 }{2814749767109}\\\\
= \frac{372916459018 }{2814749767109}
= \frac{372916459018 }{2814749767109-7*372916459018}
= \frac{372916459018 }{204334553983} \\\\
= \frac{372916459018 }{204334553983}
= \frac{372916459018-204334553983 }{204334553983}
= \frac{168581905035 }{204334553983}\\\\
= \frac{168581905035 }{204334553983}
= \frac{168581905035 }{204334553983-168581905035}
= \frac{168581905035 }{35752648948}
\\\\
\dots$$

a                             b                                q           r

59482661568307  2814749767109     21          372916459018

2814749767109      372916459018       7           204334553983

372916459018        204334553983       1           168581905035

204334553983        168581905035       1             35752648948

168581905035          35752648948       4              25571309243

35752648948             25571309243       1             10181339705

25571309243             10181339705       2               5208629833

10181339705               5208629833       1               4972709872

5208629833                 4972709872       1                 235919961

4972709872                   235919961     21                   18390691

235919961                       18390691     12                   15231669

18390691                         15231669       1                     3159022

15231669                           3159022       4                     2595581

3159022                             2595581       1                       563441

2595581                               563441       4                       341817

563441                                 341817       1                       221624

341817                                 221624       1                       120193

221624                                 120193       1                       101431

120193                                 101431       1                         18762

101431                                   18762       5                           7621

18762                                       7621       2                           3520

7621                                         3520       2                              581

3520                                           581       6                                34

581                                               34      17                                 3

34                                                    3     11                                  $$\textcolor[rgb]{1,0,0}{1}$$

3                                                      1       3                                  0

GCD = 1, so 2814749767109 and 59482661568307 are relatively prime

08.12.2014
 #5
avatar+26387 
+10

$$$\int \left(\frac{x}{\sqrt{3-4x^2}}\right)\ dx \quad \text { ?}$$$

$$\small{
\text{
$
\begin{array}{rcl}
&=&\int \left(\frac{ \big{x} }{\sqrt{3\left(1-\frac{4}{3}x^2\right)}} \right) \ dx
\\ \\
&=&\frac{1 }{\sqrt{3}}\int \left(\frac{ \big{x} }{\sqrt{ 1-
\left( \frac{ \big{x} }{ \sqrt \frac{3}{4} } \right)^2 } } \right) \ dx
\end{array}
$
}}
$\\\\$
\small\text{
we substitue: $ \frac{x} {\sqrt{ \frac{3}{4} } } = \sin(u) \quad \Rightarrow \quad \frac{ \ dx} {\sqrt{ \frac{3}{4} } } = \cos(u) \ du$
}}
$\\\\$
\small\text{
and set also: $ x = ( \sqrt{ \frac{3}{4} } ) * \sin(u) \quad $ and $\quad \ dx = ( \sqrt{ \frac{3}{4} } ) * \cos(u) \ du$
}}
$\\\\$
\small\text{
$
=\frac{1 }{\sqrt{3}}\int \left(\frac{ ( \big{ \sqrt{ \frac{3}{4} } ) * \sin(u) } }{\sqrt{ 1-
\big{ \left( \sin(u) \right)^2 } } } \right) ( \sqrt{ \frac{3}{4} } ) * \cos(u) \ du$
}}$$

$$$\\\\$
\small\text{
$
=\frac{1 }{\sqrt{3}}\int \left(
\frac{ ( \big{ \sqrt{
\frac{3}{4}
} ) * \sin(u)
}
}
{ \big{\cos(u) } }
\right) ( \sqrt{ \frac{3}{4} } ) * \cos(u) \ du$
}}
$\\\\$
\small\text{
$
=\dfrac{\frac{3}{4} }{ \sqrt{3} }\int \left(
\sin(u) \ du$
}}
$\\\\$
\small\text{
$
=\frac{ \sqrt{3}}{4}\int \left(
\sin(u) \ du$
}}
$\\\\$
\small\text{
$
=\frac{ \sqrt{3}}{4}\int \left(
\sin(u) \ du \quad | \quad \int\sin(u)\ du = -\cos(u)$
}}
$\\\\$
\small\text{
$
=\frac{ \sqrt{3}}{4}(-\cos(u))$
}}
$\\\\$
\small\text{
$
=-\frac{ \sqrt{3}}{4}\cos(u) \quad | \quad cos(u) = \sqrt{1-\sin(u)^2 }= \sqrt{1-\frac{4}{3}x^2 } $
}}
$\\\\$
\small\text{
$
=-\frac{ \sqrt{3}}{4}\sqrt{1-\frac{4}{3}x^2 } }$
}}
$\\\\$
\small\text{
$
=-\frac{1}{4}\sqrt{3-4x^2 } }$
}}$$

$$\boxed{\int \left(\frac{x}{\sqrt{3-4x^2}}\right)\ dx =-\frac{1}{4}\sqrt{3-4x^2 } \quad + c }$$

.
08.12.2014