Question

How do you know a quadratic function has exactly one zero?

Answer 1

b)

Explanation:

y = x² + 6x + 9 = (x + 3)(x + 3)

(x + 3)(x + 3) = 0, x = - 3,

or

you can find D =b² - 4ac

y = x² + 6x + 9

a = 1, b = 6, c = 9

D = 6² - 4*1*9 = 36- 36= 0

When D =0, a quadratic function has exactly one zero.