8. Which of the following is not a factor of the expression \( 5 x ^ { 2 } - 15 x \) ?
(1) \( 5 \) (3) \( 3 x \)
(2) \( x \) (4) \( x - 3\)
8. Which of the following is not a factor of the expression \( 5 x ^ { 2 } - 15 x \) ?
(1) \( 5 \) (3) \( 3 x \)
(2) \( x \) (4) \( x - 3\)
(3) 3x