Question

Seja f(x) = |2x + 2|, existem dois valores a e b, tal que a ≠ b, mas f(a) = f(b) = 4. Então, o valor de f(a + b) é igual a:
A) -2
B) -1
C) 0
D) 1
E) 2

Answer 1

f(x) = |2x + 2|

f(a) = |2a + 2|

f(b) = |2b + 2|

f(a) = f(b) = 4 => |2a + 2| = |2b + 2|

2a + 2 = -(2b + 2)

2a + 2 = -2b - 2

2a + 2b = -2 - 2

2(a + b) = -4

a + b = -2

f(a + b) = |2(a + b) + 2|

f(a + b) = |2(-2) + 2|

f(a + b) = |-4 + 2|

f(a + b) = |-2|

f(a + b) = 2

Resposta: f(a + b) = 2