SOLUTION: Find the equation of the parabola with horizontal axis which crosses the x - axis at x = 2, and the y - axis at y = -1 and y = 7.

Algebra ->  Quadratic-relations-and-conic-sections -> SOLUTION: Find the equation of the parabola with horizontal axis which crosses the x - axis at x = 2, and the y - axis at y = -1 and y = 7.       Log On


   

Question 1146374: Find the equation of the parabola with horizontal axis which crosses the x - axis at x = 2, and the y - axis at y = -1 and y = 7.
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
x=a%28y-k%29%5E2%2Bh


Vertex is for y coordinate exactly between -1 and 7;
which is 3. Also, y at -1 or +7 make the x equal to 0.

x=a%28y%2B1%29%28y-7%29

Given point (2,0):
x%2F%28%28y%2B1%29%28y-7%29%29=a
2%2F%281%2A%28-7%29%29=a
a=-2%2F7
-
highlight%28x=-%282%2F7%29%28x%2B1%29%28x-7%29%29