Algebra 1- 8th Grade
posted by Nancy .
What is the relationship between the
x-intercepts of a parabola and its vertex's x-coordinate?
if you average the x-intercepts , you get the x coordinate of the vertex.
y = x^2 - 2x - 8
so the x intercepts are 4 and -2
average of those = (-2 + 4)/2 = 1
so the vertex is (1, ...)
If I were to write down:
"When you find the median between the two intercepts, it is the x-intercept of the vertex."
do you think that's a true relationship still ?
I would use the word "mean"
"Mean" is what is known as the average in everyday language, "median" is the middle value of a set of data.
Of course if you only have two data values, as the x-intercepts, it actually does not matter.