Posted by Chelsea on Tuesday, September 21, 2010 at 2:47pm.
Find expressions for the quadratic functions whose graphs are shown. One graph has the point (4,2) plotted in which the parabola passes through (Ushaped parabola right side up) The vertex is at (3,0) and the parabola does not touch the yaxis for as much is shown.
So, I did this:
a(3)^2 + b(3) + c = 0
Solve: c = 12
For the point (4,2):
a(4)^2 + b(4)  12 = 2
Solve: 16a + 4b = 14
I am not sure if I am doing this correctly and I am also stuck at the is point. Please help.

Calculus  MathMate, Tuesday, September 21, 2010 at 5:19pm
c does not equal 12:
a(3)^2 + b(3) + c = 0
Solve: c = 9a  3b (not 12)
For the given parabola, since the vertex is (3,0), and knowing that parabolas are symmetrical with respect to the vertex, we therefore have another point (2,2), the mirror image of (4,2) about x=3 passing through the vertex.
The three known points give rise to three equations with three unknowns (a,b,c). Solve for a,b and c.