Question

Between which two ordered pairs does the graph of f(x) = x2 + x – 9 cross the negative x-axis?

Quadratic formula: x =

(–6, 0) and (–5, 0)
(–4, 0) and (–3, 0)
(–3, 0) and (–2, 0)
(–2, 0) and (–1, 0)

Answer 1

(-6,0) and (-5,0) is the correct answer

Answer 2

we have that

$f(x) =x^{2} + x - 9$

Using a graph tool

see the attached figure

The function represent a vertical parabola that open up

the vertex is a minimum-------> is the point $(-0.5,-9.3)$

The x-intercepts are the points when the y coordinate is equal to zero

The x-intercepts are the points $(-3.5,0)$ and $(2.5,0)$

so

the function cross the negative x-axis at point $(-3.5,0)$

therefore

the answer is

(–4, 0) and (–3, 0)