Răspuns:
f(1) + f(4) = f(2) + f(3) = 5a + 2b
Explicație pas cu pas:
f(1) + f(4) = f(2) + f(3)
f(x) = ax + b
f(1) = a + b
f(2) = 2a + b
f(3) = 3a + b
f(4) = 4a + b
f(1) + f(4) = a + b + 4a + b = 5a + 2b
f(2) + f(3) = 2a + b + 3a + b = 5a +2b
=> f(1) + f(4) = f(2) + f(3) = 5a + 2b
