Пошаговое объяснение:
а)
(1/2+1/3)² = (1/2)² + 2 * 1/2 * 1/3 + (1/3)² = 1/4 + 1/3 + 1/9 =
= 9/36 + 12/36 + 4/36 = 25/36,
или:
(1/2+1/3)² = (3/6 + 2/6)² = (5/6)² = 25/36;
б)
(1/2)²+(1/3)² = 1/4 + 1/9 = 9/36 + 4/36 = 13/36;
в)
(1/2)²+2*1/2*1/3+(1/3)² = 1/4 + 1/3 + 1/9 = 9/36 + 12/36 + 4/36 = 25/36,
значит:
(1/2+1/3)² = (1/2)²+2*1/2*1/3+(1/3)² = 25/36