Explicação passo-a-passo:

f) mmc(2,3,4) = 12

1/4 + 2/3 + 1/2 = (3.1 + 4.2 + 6.1)/12

1/4 + 2/3 + 1/2 = (3+8+6)/12

1/4 + 2/3 + 1/2 = 17/12

g) mmc(2,7) = 14

1/2 + 1/7 + 5/7 = (7.1 + 2.1 + 2.5)/14

1/2 + 1/7 + 5/7 = (7+2+10)/14

1/2 + 1/7 + 5/7 = 19/14

h) mmc(2,7,14) = 14

3/7 + 5/2 + 1/14 = (2.3 + 7.5 + 1.1)/14

3/7 + 5/2 + 1/14 = (6+35+1)/14

3/7 + 5/2 + 1/14 = 42/14

3/7 + 5/2 + 1/14 = 3

i) mmc(3,5,6) = 30

4/5 + 1/3 + 7/6 = (6.4 + 10.1 + 5.7)/30

4/5 + 1/3 + 7/6 = (24+10+35)/30

4/5 + 1/3 + 7/6 = 69/30

4/5 + 1/3 + 7/6 = 23/10

j) mmc(3,4,6) = 12

1/3 + 5/6 + 3/4 = (4.1 + 2.5 + 3.3)/12

1/3 + 5/6 + 3/4 = (4+10+9)/12

1/3 + 5/6 + 3/4 = 23/12