a) \(\frac{18}{15}+\frac{7}{15}+\frac{12}{15}\)

\(=\left(\frac{18}{15}+\frac{12}{5}\right)+\frac{7}{15}\)

\(=6+\frac{7}{15}\)

\(=\frac{97}{15}\)

b) \(\frac{9}{7}+\frac{8}{7}+\frac{11}{7}\)

\(=\frac{17}{7}+\frac{11}{7}\)

\(=\frac{28}{7}=4\)

TL

a) \(\frac{18}{15}+\frac{7}{15}+\frac{12}{15}\)\(=\frac{97}{15}\)

b) \(\frac{9}{7}+\frac{8}{7}+\frac{11}{7}\)\(=4\)

nha bn

HT

\(\frac{19}{11}+\left(\frac{8}{13}+\frac{3}{11}\right)=\frac{19}{11}+\frac{8}{13}+\frac{3}{11}\)

\(=\left(\frac{19}{11}+\frac{3}{11}\right)+\frac{8}{13}=2+\frac{8}{13}\)

\(=\frac{26}{13}+\frac{8}{13}=\frac{34}{13}\)

\(\frac{19}{11}+\left(\frac{8}{13}+\frac{3}{11}\right)\)

\(=\frac{19}{11}+\frac{8}{13}+\frac{3}{11}\)

\(=\left(\frac{19}{11}+\frac{3}{11}\right)+\frac{8}{13}\)

\(=2+\frac{8}{13}\)

\(=\frac{26}{13}+\frac{8}{13}=\frac{34}{13}\)

 bài làm rồi đi chép lại : )))?

\(a.32,5-3\cdot0,87=32,5-2,61=29,89\)

\(8,5\cdot\left(1\dfrac{1}{2}+\dfrac{4}{4}\right):5=8,5\cdot\left(\dfrac{3}{2}+\dfrac{4}{4}\right):5\\ =8,5\cdot\left(\dfrac{6}{4}+\dfrac{4}{4}\right):5\\ =8,5\cdot\dfrac{10}{4}:5\\ =\dfrac{85}{4}:5\\ =\dfrac{17}{4}\)

\(b.30,96-6,45+14,4:3=30,96-6,45+4,8\\ =29,31\)

\(\dfrac{2}{5}\cdot\left(\dfrac{4}{5}-\dfrac{1}{2}\right)=\dfrac{2}{5}\cdot\left(\dfrac{8}{10}-\dfrac{5}{10}\right)\\ =\dfrac{2}{5}\cdot\dfrac{3}{10}=\dfrac{3}{25}\)

bài 2

\(a.2,5\cdot12,5\cdot8\cdot0,4=\left(2,5\cdot0,4\right)\left(12,5\cdot8\right)\\ =1\cdot100=100\)

b,\(\dfrac{12}{15}\cdot\dfrac{5}{6}\cdot\dfrac{3}{20}\cdot\dfrac{32}{5}=\dfrac{12\cdot5\cdot3\cdot32}{15\cdot6\cdot20\cdot5}\\ =\dfrac{3\cdot4\cdot5\cdot3\cdot4\cdot8}{3\cdot5\cdot2\cdot3\cdot5\cdot4\cdot5}=\dfrac{16}{25}\)

Bài 1: 

a) \(32.5-3\cdot0.87=32.5-2.61=29.89\)

\(8.5\cdot\left(1\dfrac{1}{2}+\dfrac{4}{4}\right):5=8.5\cdot\dfrac{5}{2}:5=\dfrac{17}{2}\cdot\dfrac{5}{2}:5=\dfrac{85}{4}\cdot\dfrac{1}{5}=\dfrac{17}{4}\)

b) \(30.96-6.45+14.4:3=24.51+4.8=29.33\)

\(\dfrac{2}{5}\left(\dfrac{4}{5}-\dfrac{1}{2}\right)=\dfrac{2}{5}\left(\dfrac{8}{10}-\dfrac{5}{10}\right)=\dfrac{2}{5}\cdot\dfrac{3}{10}=\dfrac{6}{50}=\dfrac{3}{25}\)

12/15 + 37/7 + 16/5 + 5/7 = 10

12/15 + 37/7 + 16/5 + 5/7

= 4/5 + 37/7 + 16/5 + 5/7

= (4/5 + 16/5) + (37/7 + 5/7)

= 4 + 6

= 10

Chúc bạn học tốt.

😁😁😁

12/15 + 37/7 + 16/5 + 5/7

= ( 37/7 + 5/7 ) + ( 12/15 + 16/5 )

= 6 + ( 12/15 + 48/15 )

= 6 + 4 

= 10

Bổ ích thì k cho c em nha!

Co j góc lệch cùng trời cuối đất cú mèo

a)8/3

b,1/5 tk cho mk nha pn

b; \(\dfrac{5}{14}\) \(\times\) \(\dfrac{7}{13}\) x \(\dfrac{26}{25}\)

= \(\dfrac{5\times7\times2\times13}{7\times2\times13\times5\times5}\)

= \(\dfrac{5\times7\times2\times13}{5\times7\times2\times13}\) x \(\dfrac{1}{5}\)

= 1 x \(\dfrac{1}{5}\)

= \(\dfrac{1}{5}\)

a; \(\dfrac{21}{11}\) x \(\dfrac{22}{17}\) x \(\dfrac{68}{63}\)

= \(\dfrac{21\times11\times2\times17\times4}{11\times17\times21\times3}\)

= \(\dfrac{11\times17\times21}{11\times17\times21}\) x \(\dfrac{2\times4}{3}\)

= 1 x \(\dfrac{8}{3}\)

= \(\dfrac{8}{3}\)

14/15+3/11+1/15+3/11=10/22

=[14/15+1/15]+[3/11+3/11]

=[14/15+1/15]+[3/11*2]

= 1+6/11

=17/11

sai bet!!

3/5 x 5 + 12 x 3/5 + 3 : 5/3

=3/5 x 5 + 12 x 3/5 + 3 x 3/5

= 3/5 x ( 5 + 12 + 3 ) 

= 3/5 x 20

= 12