This table shows input and output values for a linear function f(x) . what is the positive difference of outputs for any two inputs that are three values apart? enter your answer in the box. x f(x) -3 -1.5 -2 -1 -1 -0.5 0 0 1 0.5 2 1 3 1.5

If you observer the value of x=0 and x=1, you can conclude that every 1 value of x increased, the f(x) will be increased by 0.5. The graph function should be: 
f(x)= x/2

A positive difference means that the value should be always positive. To find 3 the positive difference of f(x) with 3 values of x apart, let use x=0 and x=0+3= 3. The difference would be:
f(x+3) - f(x)
f(3)- f(0)=
1.5 - 0= 1.5
The answer would be: 1.5