SOLUTION: The vertex of this parabola is at (-3, -1). When the y-value is 0, the x-value is 4. What is the coefficient of the squared term in the parabola's equation?

Algebra ->  Quadratic-relations-and-conic-sections -> SOLUTION: The vertex of this parabola is at (-3, -1). When the y-value is 0, the x-value is 4. What is the coefficient of the squared term in the parabola's equation?      Log On


   

Question 757598: The vertex of this parabola is at (-3, -1). When the y-value is 0, the x-value is 4. What is the coefficient of the squared term in the parabola's equation?
Answer by pmatei(79) About Me  (Show Source):
You can put this solution on YOUR website!
The quadratic function can be written as
y+=+a%28x-h%29%5E2%2Bk
where (h,k) is the given vertex, and a is the coefficient of the squared term. Thus you can write:
y=a%28x%2B3%29%5E2-1
If you expand:
y=a%2Ax%5E2+%2B+6a%2Ax%2B9a-1
Replace the y with 0 and x with 4:
0+=+16a+%2B+24a+%2B+9a+-1
Solve for a:
0=+49a+-1
1=49a
1%2F49=a