Question

Rút gọn rồi tính:

a) 26/65+14/70

b)66/60-15/75

c)12/21-2/14+14/49

Answer 1

`a, = 2/5 + 1/5`

`= 3/5`

`b. = 11/10 - 2/10`

`= 9/10`

`c, = 4/7 -1/7+ 2/7`

`= 5/7`

Answer 2

a,26/65+14/70=2/5+1/5=3/5

b,66/60-15/75=11/10-1/5=9/10

c,12/21-2/14+14/49=4/7-1/7+2/7=3/7+2/7=5/7

Answer 3

a) 26/65+14/70 = 2/5+1/5=3/5.

b)66/60-15/75=11/10-2/10=9/10.

c)12/21-2/14+14/49=4/7 - 1/7 +2/7=5/7.

 

Answer 4

a.

\(\dfrac{26}{65}=\dfrac{2}{5}\\ \dfrac{14}{70}=\dfrac{1}{5}\)

\(\dfrac{26}{65}+\dfrac{14}{70}=\dfrac{2}{5}+\dfrac{1}{5}=\dfrac{3}{5}\)

b.

\(\dfrac{66}{60}=\dfrac{11}{10}\\ \dfrac{15}{75}=\dfrac{1}{5}\)

\(\dfrac{66}{60}-\dfrac{15}{75}=\dfrac{11}{10}-\dfrac{1}{5}=\dfrac{11}{10}-\dfrac{2}{10}=\dfrac{9}{10}\)

c.

\(\dfrac{12}{21}=\dfrac{4}{7}\\ \dfrac{2}{14}=\dfrac{1}{7}\\ \dfrac{14}{49}=\dfrac{2}{7}\)

\(\dfrac{12}{21}-\dfrac{2}{14}+\dfrac{14}{49}=\dfrac{4}{7}+\dfrac{1}{7}+\dfrac{2}{7}=\dfrac{7}{7}=1\)

Answer 5

`26/65 + 14/70 = 2/5 + 1/5 = 3/5`

`66/60 - 15/75 = 11/10 - 1/5 = 11/10 - 2/10 = 9/10`

`12/21 - 2/14 + 14/49 = 4/7 - 1/7 + 2/7 = 3/7 + 2/7 = 5/7`