№ 1081
1) 3,8*(-0,5) -1,8*(-0,5)= -0,5*(3,8-1,8)= -0,5*2= -1
2) -3 2/9 *2,7 -3 2/9 *(-6,3)= -3 2/9 *(2,7-6,3)= -29/9 *(-3 6/10)= -29/9 *(-36/10)= (29*36)/(9*10)= 116/10 = 11,6
3) -5/8 *4/7 +1/8 *4/7 = 4/7 *(-5/8+1/8)= 4/7 *(-4/8)= -(4*1)/7*2 =-2/7
4) 9/17 *2,1-2,1*(-8/17)= 2,1*(9/17 +8/17)= 2,1*17/17= 2,1
№1082
1) (-2 3/7 -1 5/7)*28= -29/7 *28/1= -29*4= -116
2) (2 3/5 -4 1/4)*20= (13/5 -17/4)*20= (13*4-17*5)/20 *20= (52-85)/20 *20/1 = -33/20 *20/1 = -33
3) 3 1/7 *(1 3/11 -2 5/22)= 3 1/7*(14/11 - 49/22)= 3 1/7 *(14*2-49)/22 = 22/7 * (-21/22)= -3
4) 2 7/9 *(-2 4/25 +4 8/25)= 25/9 *(-54/25 +108/25)= 25/9 * 54/25= 6