p=cov(x,y)/[√D(x)*√D(y)]cov(x,y)=E(x*y)-E(x)*E(y)=E(x^3)-E(x)*E(x^2)=E(x^3)=∫∞(x³*e^(-x²/2)/√(2π))D(x)=1,D(y)=D(x^2)=E(x^4)=∫∞(x^4*e^(-x²/2)/√(2π))