Question

Axis of symmerty x=3 passing through (3,1) and (1,9)

What is the best way to solve?

Answer 1

X = Xv = h = 3.

V(h,k)= V(3,1).
P(1,9)
Y = a(x-h)^2 + k
Y = a(1-3)^2 + 1 = 9.
4a + 1 = 9
4a = 9-1 = 8
a = 2.
Eq: Y = 2(x-3)^2 + 1

Axis: D(h,Y1), V(h,k), F(h,Y2).
Axis: D(3,Y1), V(3,1), F(3,Y2).

DV = k-Y1 = 1/4a = 1/8
1 - Y1 = 1/8
Y1 = 7/8.

VF = Y2-k = 1/4a = 1/8
Y2-1 = 1/8
Y2 = 1 1/8 = 9/8.