Find a linear function, f, given f(15)=0 and f(-5)=-4. Then find f(0).

Answer 1

If a linear function, then

f(x) = mx+b

f(15) = 0 = 15m + b

f(-5) = -4 = -5m + b Subtract the two equations to eliminate b

---------------------------

4 = 20m + 0

m = 4/20 = 1/5

0 = 15(1/5) + b

b = -3

So,

f(x) = (1/5)x -3

f(0) = -3