Question 178078
I know that the x co-ordinate of the vertex is midway between the 
2 x-intercepts, so I can use the formula
{{{x[v] = (x[1] + x[2])/2}}}
I'm told that the vertex is at (-2,-4), so {{{x[v] = -2}}},
and also given is {{{x[1] = 7}}}
{{{-2 = (7 + x[2])/2}}}
{{{-4 = 7 + x[2]}}}
{{{x[2] = -11}}}
The other x-intercept is at x = -11