Question 241788
{{{x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}} 

If the {{{b^2-4ac}}} is equal to zero then there is only one solution.

The general form of the quadratic is {{{ax^2+bx+c=0}}}

You need to rearrange your equation to that form.

so {{{-16x^2+88x-121=0}}}

So for your equation we have b=88 a=-16 and c=-121

{{{88^2-(4*-16*-121)=0}}} At this point you know there is only one solution.