Mathematics for IGCSE & O level - Sketching Curves (Section 2 - No. 19)

What is the equation of the line of symmetry for the graph of y = x² - 4x + 3?

x = -2

x = 2

y = -1

y = 1

The x coordinate of the turning point can be found with -b/2a, or completing the square to (x-2)²-1, so the line of symmetry is x=2.