Graphing a quadratic function
Answers are for parents and teachers.
1
For y = x² − 4x − 5 find the vertex, the zeros and y(0).
vertex (2, −9); zeros −1 and 5; y(0) = −5
2
For y = −2x² + 4x find the zeros, the vertex and the greatest value.
zeros 0 and 2; vertex (1, 2); greatest value 2
3
Find the greatest product of two numbers whose sum is 14.
49
4
For which x is y = x² − 9x + 14 positive?
x < 2 or x > 7
5
Can a parabola with branches pointing down and vertex below Ox meet the Ox axis? Explain.
No: the vertex is the highest point; if it is below Ox, all points are below it.