Question 839719
your equation is x^2 - 2x = 99
subtract 99 from both sides of this equation to get:
x^2 - 2x - 99 = 0
factor to get:
(x - 11) * (x + 9) = 0
solve for x to get:
x = 11 or x = -9


since there are no restrictions on the sign of the answer, both answers are good.
the graph of the equation is shown below:


{{{graph(600,600,-20,20,-150,150,x^2-2x-99)}}}


the solution to the equation are the roots of the equation which is where the graph of the equation crosses the x-axis.


your original equation is x^2 - 2x = 99
when x = 11, this becomes 121 - 22 = 99 which becomes 99 = 99.
when x = -9, this becomes 81 + 18 = 99 which becomes 99 = 99.
both solutions are good.