Answer
0; Does Not Exist; -21/2
Work Step by Step
a: $\frac{(-1)^2-2(-1)-3}{4-(-1)} = \frac{1+2-3}{5} = 0$
b: $\frac{(4)^2-2(4)-3}{4-4)} = \frac{5}{0}$ = does not exist / undefined
c: $\frac{(6)^2-2(6)-3}{4-(6)} = \frac{36-12-3}{-2} = -\frac{21}{2}$
