Let XXX have the CDF F(x)=xF(x) = xF(x)=x for x∈[0,1]x \in [0, 1]x∈[0,1]. What is the PDF f(x)f(x)f(x)?
f(x)=0f(x) = 0f(x)=0
f(x)=1f(x) = 1f(x)=1
f(x)=xf(x) = xf(x)=x
f(x)=2xf(x) = 2xf(x)=2x