Two points on a parabola are (-3,5) and (11,5). What is the equation of the axis of symmetry?
The axis of symmetry will be found by adding the x coordinates of these points and dividing by 2......so
x = [ -3 + 11] / 2
x = [ 8 ] / 2
x = 4 ⇒ axis of symmetry
This parabola opens upward
The axis of symmetry for a parabola that opens upward (or downward ) will always be the average of the two x values whenever those two x values are associated with the same y value
Thus...to find the average....add the x values and divide by 2