Answer
$a=1$
$b=-9$
$c=20$
Work Step by Step
Given:
$ax^{2} + bx + c$
$x=4$
$x=5$
Use the reverse zero factor property and equate the solns 4 and 5 by 0
$x=4$
$x-4=0$
$x=5$
$x-5=0$
Multiply the 2 equations to find the quadratic equation of the solutions
$(x-5) (x-4)=0$
$x^{2}-9x+20=0$
Notice the similarities of the quadratic equation and identify the values of a, b, and c by just observing the values
$ax^{2} + bx + c$
$x^{2}-9x+20=0$
$a=1$
$b=-9$
$c=20$
