a: y=-2x+1
=>y+2x-1=0
=>2x+y-1=0
\(d\left(O;\text{Δ}\right)=\dfrac{\left|2\cdot0+1\cdot0-1\right|}{\sqrt{2^2+1^2}}=\dfrac{1}{\sqrt{5}}\)
b: \(d\left(M;\text{Δ}\right)=\dfrac{\left|2\cdot\left(-1\right)+1\cdot\left(-3\right)-1\right|}{\sqrt{2^2+1^2}}=\dfrac{6\sqrt{5}}{5}\)