The vertex of this parabola is at (-4,-1). When the y-value is 0, the x-value is 2. What is the coefficient of the squares term in the parabola equation

A:3
B:-6
C:-3
D:6

Question

The vertex of this parabola is at  (-4,-1). When the y-value is 0, the x-value is 2. What is the coefficient of the squares term in the parabola equation 

A:3
B:-6
C:-3
D:6

bigmoee19 · Answer

Help please👍

scarlettfarra2000 · Answer

Remember that the vertex form is: y = a(x - h)² + k

zzr0ck3r · Answer

$y=a(x-h)^2+k\implies y=a(x-(-4))^2-1\ \implies y=a(x+4)^2-1$

We use the given point $(0,2)$ to solve for $a$. So let $y=2$ and $x=0$ in the above equation

$2=a(0+4)^2-1$

Can you solve for $a$?

bigmoee19 · Answer

How will i plug them in?

zzr0ck3r · Answer

I did that part. We have the equation $y=a(x+4)^2-1$ and we were given the point $(0,2)$, which means the equation is true when $x=0$ and $y=2$ So i plug in $x=0$ and $y=2$ and I get $2=a(0+4)^2-1$

Notice the difference in $y=(x+4)^2-1$ and $2=a(0+4)^2-1$.

bigmoee19 · Answer

Yes cause the equation for going left or right is with X= NOT Y=

bigmoee19 · Answer

But i will end up getting 2=a (4)^2-1

zzr0ck3r · Answer

solve for $a$

zzr0ck3r · Answer

add $1$ to both sides, and then divide both sides by $16$ and you are done.

bigmoee19 · Answer

But it wont get the anwser from above i get 5.33

zzr0ck3r · Answer

oh sorry, I thought it said $x=0$ and $y=2$ but it is the opposite. So solve this

$0=a(2+4)^2-1$

But I still don't see the right answer in the list :(