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Integral of 1/(1000-2y) dy

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The solution

You have entered [src]
  1              
  /              
 |               
 |      1        
 |  ---------- dy
 |  1000 - 2*y   
 |               
/                
0                
01110002ydy\int\limits_{0}^{1} \frac{1}{1000 - 2 y}\, dy
Integral(1/(1000 - 2*y), (y, 0, 1))
Detail solution
  1. There are multiple ways to do this integral.

    Method #1

    1. Let u=10002yu = 1000 - 2 y.

      Then let du=2dydu = - 2 dy and substitute du2- \frac{du}{2}:

      (12u)du\int \left(- \frac{1}{2 u}\right)\, du

      1. The integral of a constant times a function is the constant times the integral of the function:

        1udu=1udu2\int \frac{1}{u}\, du = - \frac{\int \frac{1}{u}\, du}{2}

        1. The integral of 1u\frac{1}{u} is log(u)\log{\left(u \right)}.

        So, the result is: log(u)2- \frac{\log{\left(u \right)}}{2}

      Now substitute uu back in:

      log(10002y)2- \frac{\log{\left(1000 - 2 y \right)}}{2}

    Method #2

    1. Rewrite the integrand:

      110002y=12(y500)\frac{1}{1000 - 2 y} = - \frac{1}{2 \left(y - 500\right)}

    2. The integral of a constant times a function is the constant times the integral of the function:

      (12(y500))dy=1y500dy2\int \left(- \frac{1}{2 \left(y - 500\right)}\right)\, dy = - \frac{\int \frac{1}{y - 500}\, dy}{2}

      1. Let u=y500u = y - 500.

        Then let du=dydu = dy and substitute dudu:

        1udu\int \frac{1}{u}\, du

        1. The integral of 1u\frac{1}{u} is log(u)\log{\left(u \right)}.

        Now substitute uu back in:

        log(y500)\log{\left(y - 500 \right)}

      So, the result is: log(y500)2- \frac{\log{\left(y - 500 \right)}}{2}

    Method #3

    1. Rewrite the integrand:

      110002y=12y1000\frac{1}{1000 - 2 y} = - \frac{1}{2 y - 1000}

    2. The integral of a constant times a function is the constant times the integral of the function:

      (12y1000)dy=12y1000dy\int \left(- \frac{1}{2 y - 1000}\right)\, dy = - \int \frac{1}{2 y - 1000}\, dy

      1. Let u=2y1000u = 2 y - 1000.

        Then let du=2dydu = 2 dy and substitute du2\frac{du}{2}:

        12udu\int \frac{1}{2 u}\, du

        1. The integral of a constant times a function is the constant times the integral of the function:

          1udu=1udu2\int \frac{1}{u}\, du = \frac{\int \frac{1}{u}\, du}{2}

          1. The integral of 1u\frac{1}{u} is log(u)\log{\left(u \right)}.

          So, the result is: log(u)2\frac{\log{\left(u \right)}}{2}

        Now substitute uu back in:

        log(2y1000)2\frac{\log{\left(2 y - 1000 \right)}}{2}

      So, the result is: log(2y1000)2- \frac{\log{\left(2 y - 1000 \right)}}{2}

  2. Add the constant of integration:

    log(10002y)2+constant- \frac{\log{\left(1000 - 2 y \right)}}{2}+ \mathrm{constant}


The answer is:

log(10002y)2+constant- \frac{\log{\left(1000 - 2 y \right)}}{2}+ \mathrm{constant}

The answer (Indefinite) [src]
  /                                   
 |                                    
 |     1               log(1000 - 2*y)
 | ---------- dy = C - ---------------
 | 1000 - 2*y                 2       
 |                                    
/                                     
110002ydy=Clog(10002y)2\int \frac{1}{1000 - 2 y}\, dy = C - \frac{\log{\left(1000 - 2 y \right)}}{2}
The graph
0.001.000.100.200.300.400.500.600.700.800.900.0009980.001004
The answer [src]
log(1000)   log(998)
--------- - --------
    2          2    
log(998)2+log(1000)2- \frac{\log{\left(998 \right)}}{2} + \frac{\log{\left(1000 \right)}}{2}
=
=
log(1000)   log(998)
--------- - --------
    2          2    
log(998)2+log(1000)2- \frac{\log{\left(998 \right)}}{2} + \frac{\log{\left(1000 \right)}}{2}
log(1000)/2 - log(998)/2
Numerical answer [src]
0.00100100133533654
0.00100100133533654

    Use the examples entering the upper and lower limits of integration.