The joint density function f(x,y) for two random variables x,Y is given by f(x,y)={(12/7)*(x³+y²), if 0<=x,y<=1),(0, otherwise ):} Find
a) the value of f(1,1)
b) the value of f(0,0)
c) the value of f(0.5,0.5)
d) the value of f(2,2)