Question

verifique quais dos valores de x a seguir sao raizes da funcao y=x2-2x-8
x=1
x=2
x=3
x=4
x=5

Answer 1

y=x^2-2x-8
x^2-2x-8=0
delta=b^2-4.a.c
delta=(-2)^2-4.1.(-8)
delta=4+32
delta=36
x=-b-/+ raiz de delta / 2a
x=-(-2)-6/2.1
x=2-6/2
x=-4/2
x=-2
x=-(-2)+6/2.1
x=2+6/2
x=8/2
x=4