function from vertex and point

• Oct 12th 2009, 04:03 PM
yellow24
function from vertex and point
im given a vertex and a point yet every time i try i cant get the formula write, the book only gives me the answer showing tat im wrong every time, any help?

ex. pt (2,-3)
vertex (1,-4)
• Oct 12th 2009, 04:08 PM
mr fantastic
Quote:

Originally Posted by yellow24
im given a vertex and a point yet every time i try i cant get the formula write, the book only gives me the answer showing tat im wrong every time, any help?

ex. pt (2,-3)
vertex (1,-4)

$y = a(x - h)^2 + k$ has a vertex at (h, k).

Therefore $y = a(x - 1)^2 - 4$.

Now substitute (2, -3) and solve for $a$.
• Oct 12th 2009, 04:09 PM
yellow24
thank you... i tried doing it another way but that one works too. thanks again!