Question

Find the equation f(x) = a(x - h)2 + k for a parabola containing point (3, 6) and having (1, -2) as a vertex. What is the standard form of the equation?

Answer 1

f(x) = 2
`x^(2)` -4x

Explanation:

Step 1 :

Given, f(x) = a(x - h)2 + k

Point on the parabola is (3, 6)

Vertex (h,k) = (1,-2)

Step 2:

Substituting the vertex in the equation we have,

f(x) = a(x-1)2 -2

Substituting the point (3,6) in this we have,

6 = a(3-1)2 - 2 => 6 = 4a -2

=> 4a = 8 => a = 2

Step 3 :

Substituting the value for a and the vertex in the given equation we have

f(x) = 2(x-1)2 -2 = 2(x2 - 2x + 1) -2 = 2x2 - 4x

=> f(x) = 2
`x^(2)` -4x which is the standard form