The function y = ax² + bx + c
Answers are for parents and teachers.
1
Find the vertex of y = x² − 8x + 3.
(4, −13)
2
Write the equation of the parabola with vertex (−1, 3) that passes through (1, 7).
y = (x + 1)² + 3 = x² + 2x + 4
3
Write y = x² + 10x + 21 by completing the square.
y = (x + 5)² − 4
4
Write the equation of the parabola obtained by shifting y = 2x² one unit left and four units up.
y = 2(x + 1)² + 4
5
For y = x² − 2x − 3 compute y(0) and y(2) and explain what this says about the axis of symmetry.
y(0) = y(2) = −3; the points are equally far from x = 1, so the axis of symmetry is x = 1.