Выполните умножение: а) 2/7 × (- 5 1/4) б) - 4 1/2 × (-1 1/3) в) 3,6 × (- 2/3) г) - 4/7 × 4.2 д) -2.8 × (-1 1/7) е) -2

а) 2/7 * (- 5 1/4) = 2/7 * (- 21/4) = - (2 * 21)/(7 * 4) = - (1 * 3)/(1 * 2) = -3/2 = - 1 1/2; б) - 4 1/2 * (-1 1/3) = -9/2 * (-4/3) = (9 * 4)/(2 * 3) = (3 * 2)/(1 * 1) = 6/1 = 6; в) 3,6 * (- 2/3) = 36/10 * (-2/3) = 18/5 * (-2/3) = -(18 * 2)/(5 * 3) =-(6 * 2)/(5 * 1) = -12/5 = - 2 2/5; г) - 4/7 * 4.2 = -4/7 * 42/10 = -4/7 * 21/5 = -(4 * 21)/( 7 * 5) = -(4 * 3)/( 1 * 5) = -12/5 = -2 2/5; д) -2.8 * (-1 1/7) = -28/10 * 8/7 = -(28 * 8)/(10 * 7) = -(4 * 4)/(5 * 1) = - 16/5 = -3 1/5; е) -2 1/3 * 0,125 = -7/3 * 125/1000 =- (7 * 125)/(3 * 1000) = - (7 * 1)/(3 * 8) =-7/24.