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.
Begin to write a function in factored form. f(x) = a(x + 1)(x - 5)
Substitute to determine a.
1-25 = a(0+1)(0-5)
Simplify and solve to find a.
-5
Rewrite the function.
f(x)=5(x+1)(x-5)
Rewrite in standard form.
.
f(x) = 5x2–20x-25
Find the x-coordinate of the vertex.
-20 -20. y_
^ 2(5) - 10
Find the y-coordinate of the vertex. y=5x2–20x-25
y=5(-2)2 - 20(-2)-25
y=35 so (-2,35)
Which best describes the first error in Jan'ai's work?
O
She incorrectly determined the factors for the beginning function.
She incorrectly determined the a value.
She incorrectly transformed the equation to standard form.
O​