Distribution of order statistics

I have the following function

     $(x^{1-2r})(1-r)$/${2/3}^r$ + ${(1- 
     x)^{1-2r}$/${1/3}^r$

Where, 0<=x<=1 and 0<=r<=1

I want to plot it by taking particular value of r at a time. For example, distribution of x for r=1/2, and so on...

The graph should look something like -

How can I do that in matlab. Any help will be highly appreciated. Please help me.