Question

If f is a linear function, f(k)=16 and f(-k)= -4 then what is the value of f(0)?​

Answer 1

f(0) =  ( f(k) +f(-k) ) / 2

f(0) = (16 - 4) / 2

f(0) = 12 / 2

f(0) = 6  → ANSWER

*Remember that f(0) = m(0) + n = n

If we have f(x) = mx + n, then:

f(k)= mk + n     and       f(-k)= -mk + n

If we add them:

  f(k) + f(-k)

= mk + n -mk + n

= 2n

= 2f(0)

So we conclude that:

f(0) = [f(k) + f(-k)] / 2