Which of the following expressions are undefined?
Find the roots of the following equations
(1) x(x − 3) = 0
(2) a(a + 5) = 0
(3) m2 − 4m = 0
(4) 3k2 + 6k = 0
(5) (y + 6) (y + 9) = 0
(6) (b − 3) (b − 5) = 0
(7) (2n + 1) (3n − 2) = 0
(8) (5z − 2) (7z + 3) = 0