Question 127256
To find the axis of symmetry, use this formula:


{{{x=-b/(2a)}}}


From the equation {{{y=-x^2-10x+7}}} we can see that a=-1 and b=-10


{{{x=(--10)/(2*-1)}}} Plug in b=-10 and a=-1



{{{x=10/(2*-1)}}} Negate -10 to get 10



{{{x=(10)/-2}}} Multiply 2 and -1 to get -2




{{{x=-5}}} Reduce



So the axis of symmetry is  {{{x=-5}}}