Write the equation of the quadratic function with roots -9 and and -3 and a vertex at (-6, -1).

Question

anonymous · Answer

start with $a(x+9)(x+3)$ and then solve for $a$

anonymous · Answer

or start with $f(x)=a(x+6)^2-1$ and solve for $a$ either way. 
you need the steps?

anonymous · Answer

@Traxter ?

anonymous · Answer

Ok, so you have y= a(x+9)(x+3) and you need to find a.
If we put in x=-6, y=-1 we get:
$$-1=a(3)(-3)$$
$$-1=-9a$$
$$a=\frac{1}{9}$$
So we have $$y=\frac{1}{9}(x+9)(x+3)$$

anonymous · Answer

Please let me know if I can make anything more clear :)

anonymous · Answer

so that would be the final answer?

anonymous · Answer

or equation

anonymous · Answer

@Traxter

anonymous · Answer

$$y=\frac{1}{9}(x+9)(x+3)$$
Or you could expand it:
$$y=\frac{1}{9}(x^2+12x+27)$$
$$y=\frac{x^2}{9}+\frac{4}{3}x+3$$

anonymous · Answer

You alright with that?

anonymous · Answer

yes.thank you :)

anonymous · Answer

No worries :)