Question

Jan'ai was asked to determine the minimum for a function with zeros located at –1 and 5, which also has a y-intercept of (0, –25). Her work is shown.



Which best describes the first error in Jan'ai's work?

She incorrectly determined the factors for the beginning function.
She incorrectly determined the a value.
She incorrectly transformed the equation to standard form.
She incorrectly determined the x-coordinate of the vertex.

Answer 1

She incorrectly determined the factors for the beginning function.

Reason: zeros at -1 and 5 give factors (x + 1)(x - 5). Using the y‑intercept (0, −25) yields a(1)(−5) = −25 so a = 5, and the parabola is y = 5(x + 1)(x − 5) with vertex at x = 2 and minimum y = −45.