Question

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

Answer 1

(-6,0) and (-5,0) I got it right

Answer 2

Answer: It must be between two ordered pair i.e. (-4,0) and (-3,0).

Step-by-step explanation:

Since we have given that

Quadratic equation : $x^2+x-9$

First we use the quadratic formula to get the value of x:

$x=\dfrac{-b\pm\sqrt{b^2-4ac}}{2a}\\\\x=\dfrac{-1\pm\sqrt{1+36}}{2\times 1}\\\\x=\dfrac{-1\pm\sqrt{37}}{2}\\\\x=\dfrac{-1+\sqrt{37}}{2}\ or\ \dfrac{-1-\sqrt{37}}{2}\\\\x=2.54\ or\ -3.5$

Since the negative root of x is -3.5.

So, it must be between two ordered pair as follows :

(-4,0) and (-3,0).