Alberta Free Tutoring And Homework Help For Math 31

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Integrate by parts x/ (x-1)^(1/2)

3 years ago

Answered By Majid B

 $\int\frac{x}{\left(x-1\right)^{\frac{1}{2}}}dx$x(x1)12  dx $=$= $\int u.dv=u.v-\int v.du$∫u.dv=u.v∫v.du

 $x=u$x=u    =>    $dx=du$dx=du 

$\frac{dx}{\left(x-1\right)^{\frac{1}{2}}}=dv$dx(x1)12  =dv     =>    $2\left(x-1\right)^{\frac{1}{2}}=v$2(x1)12 =v 

        $\int\frac{x}{\left(x-1\right)^{\frac{1}{2}}}dx=x.\left(2\left(x-1\right)^{\frac{1}{2}}\right)-\int2\left(x-1\right)^{\frac{1}{2}}.dx=2x\left(x-1\right)^{\frac{1}{2}}-2\left(\frac{\left(x-1\right)^{\frac{3}{2}}}{\frac{3}{2}}\right)+C=2x\left(x-1\right)^{\frac{1}{2}}-\frac{4}{3}\left(x-1\right)^{\frac{3}{2}}+C=\frac{1}{3}\left(x-1\right)^{\frac{1}{2}}\left(6x-4x+4\right)+C=\frac{1}{3}\left(x-1\right)^{\frac{1}{2}}\left(2x+4\right)+C=\frac{2}{3}\left(x-1\right)^{\frac{1}{2}}\left(x+2\right)+C$x(x1)12  dx=x.(2(x1)12 )∫2(x1)12 .dx=2x(x1)12 2((x1)32 32  )+C=2x(x1)12 43 (x1)32 +C=13 (x1)12 (6x4x+4)+C=13 (x1)12 (2x+4)+C=23 (x1)12 (x+2)+C    


3 years ago

Answered By Michael Z

1. Let u=x and dv= $\frac{1}{\sqrt{x-1}}$1x1  , then du=dx and v= $2\left(x-1\right)^{\frac{1}{2}}$2(x1)12  [hint use substitution]

2.integration by parts formula is  $\int udv=uv-\int vdu$∫udv=uv∫vdu 

3. substitute:   $\int\frac{x}{\sqrt{x-1}}=\left(x\right)\left(2\left(x-1\right)^{\frac{1}{2}}\right)-\int2\left(x-1\right)^{\frac{1}{2}}dx$xx1 =(x)(2(x1)12 )∫2(x1)12 dx  

4. integrate:  $\int2\left(x-1\right)^{\frac{1}{2}}dx=\frac{4\left(x-1\right)^{\frac{3}{2}}}{3}+c$∫2(x1)12 dx=4(x1)32 3 +c  [hint use substitution]

5. solution is:   $\int\frac{x}{\sqrt{x-1}}=\left(x\right)\left(2\left(x-1\right)^{\frac{1}{2}}\right)-\frac{4\left(x-1\right)^{\frac{3}{2}}}{3}+c$xx1 =(x)(2(x1)12 )4(x1)32 3 +c