Question 85287
a is a relation and a function since all of the x-coordinates are different. The domain is {1,4,6 and 2} and the range is {1,1,2 and 0}

b is a relation, not a function,  since two ordered pairs have the same x-coordinate ; (1 , 2) and (1 , 3). The domain is {1 , 3 and 2} and the range is {2,1,3 and 0}

c is a relation and a function since every x-coordinate is mapped uniquely on to the y-value of 5. The domain is {all real numbers} and the range is {5}

d is a function and a relation, since each x-value maps on to one unique y-value. The domain is {all real numbers except 1/2} [if x = 1/2, you get a 0 denominator which can't be] and the range is {all real numbers except 0} [the denominator cant ever be 0 and the numerator is always 6, so the expression {{{6/(2x-1)}}} will never have the value 0]