Пошаговое объяснение:
N° 1
A) 1. 2/5 + 3. 7/15 = 7/5 +52/15=21/15 + 52/15 =73/15=4. 13/15
Б) 4. 3/14 -1. 2/21=59/14-23/21=177/42 - 46/42= 131/42= 3. 5/42
В) 3. 5/6 + 2. 7/15 - 1. 29/30 = 23/6 + 37/15 - 59/30= 115/30 + 74/30 - 59/30= 189/30 - 59/30 = 130/30=13/3=4. 1/3
N°2
А) 4. 1/6 • 3. 3/5 = 25/6 •18/5=5•3=15
Б) 1. 2/13 : 1. 4/11 = 15/13 : 15/11 = 15/13 • 11/15 = 11/13
В) 2. 2/3 • 1. 1/8 : 6. 2/3 = 8/3 • 9/8 : 20/3 = 3 : 20/3 = 3 • 3/20 = 9/20
N°3
2 : 2. 2/3 + 1. 4/5 • 3. 1/3 - 2. 5/6 =3. 1/12
1) 2 : 8/3 = 2 • 3/8 = 3/4
2) 9/5 •10/3 = 6
3) 3/4 + 6/1 = 3/4 + 24/4 = 27/4
4) 27/4 - 17/6 = 71/12 - 34/12 = 37/12 =3. 1/12
450см² = 450см²:10000 = 0.045м²