Answer
a) The rate of change is $1$.
b) $f(x)=x+3$.
Work Step by Step
a) The rate of change (slope) can be calculated from two points:
$\frac{f(y)-f(x)}{y-x}=\frac{f(1)-f(0)}{1-0}=\frac{4-3}{1-0}=\frac{1}{1}=1$.
b) $f(x)=3$ at $x=0$, so the y-intercept is $b=3$. Hence, we have: $f(x)=x+3$.
