What is the axis of symmetry for the graph of y – 4x = 7 – x2 ? a) x = 2 b) y = 2 c) x = 11 d) y = 11

Equation: y – 4x = 7 – x^2 ?

=> y = -x^2 + 4x + 7

The axis of symmetry is the vertical line that passes through the vertex.

So find the vertex of y = - x^2 + 4x + 7

You can complete squares:

1) y = - [x^2 - 4x] + 7

2) y = - [ (x - 2)^2 - 4] + 7

3) y = - (x - 2)^2 + 4 + 7

4) y = -(x - 2)^2 + 11

The vertex is (2,11), and the symmetry line is x = 2

option A. x = 2