Answer: the roots are x = 20 and x = -8
Step-by-step explanation:
We have the function
y = (1/4)x^2 - 3x - 40
We want to find the roots, that are the points in where y(x) = 0
For a quadratic equation of the form:
y = a*x^2 + bx + c the roots are:
[tex]x = \frac{-b +-\sqrt{b^2 -4*a*c} }{2*a}[/tex]
in this case we have:
[tex]x = \frac{3 +-\sqrt{3^2 +4*(1/4)*40} }{2*(1/4)}= \frac{3 +-7}{(1/2)}[/tex]
So the two roots are:
x = 2*(3 + 7) = 20
x = 2*(3 - 7) = -8
