Expert: Abe Mantell - 5/30/2009

Question
I am studying for my diploma exam test can you help me with Part A questions ( 1,2,3) on this page:

http://education.alberta.ca/media/930712/03%20pure30%20feb-09%20skydiving%20stud...


Answer
Hello Kira,

1. The vertex of the parabola is at (0,11), so we can write the
-  equation as y=a(x-0)^2 + 11, as for "a"...we know that when
-  y=0, x=3...so: 0=a(3)^2 + 11, so a=-11/9
-  Thus, y=-(11/9)x^2+11

2. Moving the origin over 2 units to the left, is equivalent to
-  moving the parabola 2 units to the right...so the equation
-  would be y=-(11/9)(x-2)^2 + 11

3. set y=0 and solve for x:
-  0-12250 = -(4.9/62500)x^2 ==> x^2 = 12250*62500/4.9
-  so x is 12500 ==> coordinates (12500, 0)

OK?  I hope this helps...

Abe