Manipulate[​​Plot[a^2*vx+(1-a)^2*vy+2*a*(1-a)*cxy,{a,0,1},AxesOrigin{0,0},AxesLabel{a,"Var(aX + (1-a)Y)"}],​​{{vx,0.5,"Var(X)"},0,1},{{vy,0.5,"Var(Y)"},0,1},{{cxy,0,"Cov(X,Y)"},-1,1}]
In[]:=
​
Var(X)
Var(Y)
Cov(X,Y)
Out[]=
pub=CloudPublish[EvaluationNotebook[]]
In[]:=
CloudObject
https://www.wolframcloud.com/obj/6c448f95-eb7a-45c8-a7c3-490350c07882

Out[]=
​