211

a) tosi
f\left(-1\right)=\left(-1\right)^2-2\cdot\left(-1\right)-3
3-3=0
f\left(3\right)=3^2-2\cdot3-3
9-6-3=0
b) epätosi
f\left(-1\right)=\left(-1\right)^2-2
1-2=-1(-3)
c) tosi