write the equation of the quadratic function with roots -10 and -8 and a vertex at (-9,-3).
help please awarding medal.

Question

write the equation of the quadratic function with roots -10 and -8 and a vertex at (-9,-3).
help please awarding medal.

anonymous · Answer

@whpalmer4

anonymous · Answer

@Mertsj (Moderator)

mertsj · Answer

If -10 is a root, then x+10 is a factor.  If -8 is a root, then x+8 is a factor
So we have:  y= a(x+10)(x+8)
Plug in the given point and find a

anonymous · Answer

im not sure what to do just plug in -8 ?

mertsj · Answer

What is the given point?

anonymous · Answer

oh um..-10??

mertsj · Answer

Read the problem.  In the problem there is a point given.

anonymous · Answer

-9?

mertsj · Answer

Do you know that points have an x coordinate and a y coordinate?
They are usually expressed in the form of an ordered pair.

anonymous · Answer

yea i havent ever done this before so i dont know anything about it

mertsj · Answer

Replace x with -9 and y with -3 and find a
(-9,-3) is an ordered pair.  It designates a certain point.  The x coordinate of the point is -9.  That means go 9 to the left on the x axis.  The y coordinate of the point is -3.  That means go down 3 from the y axis.

anonymous · Answer

okay so how do i find the equation now

anonymous · Answer

how do i solve for a

mertsj · Answer

Get a by itself.