2 2 3 (4 − 6 ): 2 • 2 3 4 − 6 2 2 3 2 (4 − 6 ): 2 = 2 2 2 3 4 6 = − 2 2 4 6 = ( × 2−1 × 3−1 ) − ( × y 1−1 × 2−1 ) 2 2 0 = − • = 1; ≠ 0 1 • = • 2 3 4 − 6 2 2 3 2 (4 − 6 ): 2 = 2 2 2 × 2 × 2 3 4 = × × = − 2 2 2 2 6 = × × × 2 2 = × × = − × ×