The vertex will be when the velocity is equal to zero:
df/dx=-12x+24 (using the power rule for differentiation)
df/dx=0 only when:
-12x+24=0 add 12x to both sides
12x=24 divide both sides by 12
x=2, we find the y value to be:
y(2)=-6(2^2)+24*2-20
y(2)=-24+48-20=4
So the vertex is the point (2,4)
And the axis of symmetry is the line x=2
Now if you do not yet do calculus...
The vertex will occur midway between the two zeros.
6x^2-24x+20=0 (using the Quadratic Formula for simplicity)
x=(24±√96)/12
x≈(1.1835, 2.8165)
Now the vertex occurs at the average of the zeros...
x=(1.1835+2.8165)/2=2 (as we saw earlier)
y(2)=4
Vertex is at (2,4) and axis of symmetry is the vertical line x=2
