Question

f(x)=-x² +2x +8 zero da funçao

Answer 1

-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=-8/-2
x=4
x=-2+6/2.(-1)
x=4/-2
x=-2

Answer 2

Δ = b² - 4ac
Δ = 2² - 4 .(-1) . 8
Δ = 4 + 32
Δ = 36

x' = -2 + √36
         2(-1)
x' = (-2 + 6) / -2
x' = 4 / (-2)
x' = -2
=============================
x" = -2 - 6
         -2
x" = -8 / (-2)
x" = 4

f(x) = 0 para x = -2 ou x = 4