P(x)=2/π*(e^x/(1+e^(2x))] P(Y=1)=P(X>=0)=∫(0,+∞)2/π*(e^x/(1+e^(2x))]dx=2/π*arctane^x|(0,+∞) =2/π(π/2-π/4)=1/2 P(Y=-1)=P(X>=0)=∫(-∞,0)2/π*(e^x/(1+e^(2x))]dx=2/π*arctane^x|(-∞,0) =2/π(π/4-0)=1/2
