The centre of the circle z¯z−(2+3i)z−(2−3i)¯z+9 = 0 is
How many of the following are functions ?
(i) f(x) = x5;{−1,0,1}→{0,1,2}
(ii) f(x) = ±√x;{0,4,9}→{0,2,−2,3,−3}
(iii) f(x) = √x;{0,4,9}→{0,2,−2,3,−3}
(iv) f(x) = x2;{0,1,2}→{0,1,2,3,4}