Question

Sendo f(x) = x^2 -6x +8 , determine:
a)f( -2 ) + f( 0 ) b) o valor de x quando f( x ) = 3

Answer 1

a) f(-2) = (-2)² - 6(-2) + 8
          = 4 + 12 + 8 
          = 24
 
    f(0) = 0² - 6  0 + 8
          = 8

b) f(x) = 3
    3 = x² - 6x + 8
    x² - 6x + 5 = 0
Δ = (-6)² - 4 . 1 . 5
Δ = 36 - 20
Δ = 16
x1 = 6 + 4 / 2 = 10 / 2 = 5
x2 = 6 - 4 / 2 = 2 / 2 = 1