Question

3) Sendo f(x) = 3. x – 5, calcule o valor de [ f(-5) – f(-2)] : f(0).

Answer 1

f(x) = 3x - 5

f(-5) = 3.(-5) - 5 = -20

f(-2) = 3.(-2) - 5 = -11

f(0) = 3.0 - 5 = -5

Temos então

[ f(-5) - f(-2) ] : f(0)

[ -20 - (-11) ] : -5

[ -20 + 11 ] : -5

[ -9 ] : -5

9/5

Answer 2

f(-5) = 3 · (-5) - 5 = -15 - 5 ∴ f(-5) = -20

f(-2) = 3 · (-2) - 5 = -6 - 5 ∴ f(-2) = -11

f(0) = 3 · 0 - 5 = 0 - 5 ∴ f(0) = -5

[f(-5) – f(-2)] : f(0) = [-20 - (-11)] : (-5) = [-20 + 11] : (-5) = (-9) : (-5) = 9/5 ou 1,8.