Question 978909
Begin with standard form,  {{{y=a(x-h)^2+k}}}.
Solve for a because you will also use the formula.


{{{y-k=a(x-h)^2}}}
{{{a=(y-k)/(x-h)^2}}}
Use the given vertex and y-intercept:
{{{a=(240-245)/(0-1)^2}}}
{{{a=-5/1}}}
{{{a=-5}}}


Solve the standard form equation for the two x-intercepts.  (Let y=0  and just solve for the value of x, which then gives the x-intercepts.)
{{{y=-5(x-1)^2+245}}}
{{{-5(x-1)^2=-245}}}-----y has been set equal to 0 but step not shown
{{{(x-1)^2=-245/-5}}}
{{{(x-1)^2=49}}}
{{{x-1=0+- 7}}}
{{{x=1+- 7}}}
Either x=-6  or  x=8
As ordered pair points,  (-6,0)  and  (8,0) are the x-intercepts.