Question

Tính :

a) 1/2 + 1/3 + 1/4.

b) 2/3 + 3/4 + 4/5.

c) 6/5 + 4/3 + 7/9.

d) 8/9 - 5/6.

e) 15/17 - 11/13.

Ai làm đúng mình sẽ tick.

Answer 1

1/2 + 1/3 + 1/4 = 6/12 + 4/12 + 3/12 = 13/12

2/3 + 3/4 + 4/5 = 8/12 + 9/12 + 4/5 = 17/12 + 4/5 = 85 / 60 +  48 / 60 = 133/ 60

6/5 + 4/3 + 7/9 = 18/ 15 + 20/15 + 7/9 = 38 /15 + 7/ 9 = 114/45 +35/45 = 149/45

8/9 - 5/6 = 16/18 - 15/18 = 1/18 

15/17 - 11 /13 = 195/221 -187/221= 8/221

Answer 2

a) \(\frac{1}{2}+\frac{1}{3}+\frac{1}{4}\)

= \(\frac{6}{12}+\frac{4}{12}+\frac{3}{12}\)

= \(\frac{13}{12}\).

b) \(\frac{2}{3}+\frac{3}{4}+\frac{4}{5}\)

= \(\frac{8}{12}+\frac{9}{12}+\frac{4}{5}\)

= \(\frac{17}{12}+\frac{4}{5}\)

= \(\frac{85}{60}+\frac{48}{60}\)

= \(\frac{133}{60}\).

c)\(\frac{6}{5}+\frac{4}{3}+\frac{7}{9}\)

= \(\frac{54}{45}+\frac{62}{45}+\frac{35}{45}\)

= \(\frac{151}{45}\).

d) \(\frac{8}{9}-\frac{5}{6}\)

= \(\frac{16}{18}-\frac{15}{18}\)

= \(\frac{1}{18}\).

e) \(\frac{15}{17}-\frac{11}{13}\)

= \(\frac{195}{221}\)\(-\frac{187}{221}\)

= \(\frac{8}{221}\).