А) 1 1/4 - 1/3 = 1 3/12 - 4/12 = 15/12 - 4/12 = 11/12
Общий знаменатель 12
12 : 4 = 3 - доп.множ. к 1/4 = (1*3)/(4*3) = 3/12
12 : 3 = 4 - доп.множ. к 1/3 = (1*4)/(3*4) = 4/12
Б) 1 1/3 - 5/6 = 1 2/6 - 5/6 = 8/6 - 5/6 = 3/6 = 1/2
Общий знаменатель 6
6 : 3 = 2 - доп.множ. к 1/3 = (1*2)/(3*2) = 2/6
3/6 = 1/2 - сократили на 3
В) 3 1/8 - 1/6 = 3 3/24 - 4/24 = 2 27/24 - 4/24 = 2 23/24
Общий знаменатель 24
24 : 8 = 3 - доп.множ. к 1/8 = (1*3)/(8*3) = 3/24
24 : 6 = 4 - доп.множ. к 1/6 = (1*4)/(6*4) = 4/24
Г) 13 1/24 - 1 11/16 = 13 2/48 - 1 33/48 = 12 50/48 - 1 33/48 = 11 17/48
Общий знаменатель 48
48 : 24 = 2 - доп.множ. к 1/24 = (1*2)/(24*2) = 2/48
48 : 16 = 3 - доп.множ. к 11/16 = (11*3)/(16*3) = 33/48
Д) 13 1/8 - 10 3/16 = 13 2/16 - 10 3/16 = 12 18/16 - 10 3/16 = 2 15/16
Общий знаменатель 16
16 : 8 = 2 - доп.множ. к 1/8 = (1*2)/(8*2) = 2/16
Е) 16 2/25 - 12 2/15 = 16 6/75 - 12 10/75 = 15 81/75 - 12 10/75 = 3 71/75
Общий знаменатель 75
75 : 25 = 3 - доп.множ. к 2/25 = (2*3)/(25*3) = 6/75
75 : 15 = 5 - доп.множ. к 2/15 = (2*5)/(15*5) = 10/75