4 Answers

75 = (x^2 + 5x) 

            200

Multiply both sides by 200

200(75 = (x^2 + 5x) 

                    200

15000 = x^2 + 5x

To solve, I would rewrite the equation so I could solve it by using the Quadratic Formula.

Quadratic Formula: ax^2 + bx + c = 0    

x^2 + 5x = 15000  

x^2 + 5x -15000 = 0  >  a = 1,  b = 5,  c = -15000

x = -5 +- square root of (5)^2 - 4(1)(-15000)  

                              2(1)

      -5 +- square root of 60025   

                        2

            -5 +- 245    

                  2

  x =    -5 + 245   and  x =   -5 - 245   

                2                              2

         x = 120    and      x = -125 

120

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X can be 120 or X can be -125