Question 432649
  <pre><font face = "Tohoma" size = 4 color = "indigo"><b>
Hi
solving Proportions by cross multiplying
      {{{(a+1)/ 2 = (a - 1)/9}}}   |CROSS MULTIPLYING
      9(a+1) = 2(a-1) 
         7a = -11
          a = -11/7

     {{{3/b = b / 9 }}}
      b^2 = 27
      b = ± sqrt(27)

  {{{5 /x = (x - 1)/ 3}}}
    x(x-1) = 15
   x^2 -x - 15 = 0 
{{{x = (1 +- sqrt(61 ))/(2) }}}