Respuesta :

if f(x) = 0 then it is a root

x + 3 = 0
x=-3
f(-3) = (-3)^4 + 10(-3)^3 + 23(-3)^2 - 34(-3) - 120 = 0

x - 2 = 0
x=2
f(2) = (2)^4 + 10(2)^3 + 23(2)^2 - 34(2) - 120 = 0