Question

What is the axis of symmetry and vertex for the graph `y = -x^2 – 2x – 13`?

Answer 1

`x=-1, (-1,-12)`

Explanation:

`"for the standard quadratic function " y=ax^2+bx+c`

`"equation of axis of symmetry is " x=-b/(2a)=x_(color(red)"vertex")`

`"for " y=-x^2-2x-13`

`"then " a=-1,b=-2" and " c=-13`

`"equation of axis of symmetry " =-(-2)/(-2)=-1`

`rArr" axis of symmetry " x=-1`

`"substitute this value into function and evaluate for y"`

`y_(color(red)"vertex")=-(-1)^2-2(-1)-13=-12`

`rArrcolor(magenta)"vertex " =(-1,-12)`