7 phan 8 bang bao nhieu

a)  A =1 /57

b)  B = 1/41

K MIK NHA

A = 1/57

B = 1/41

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

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

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

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

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

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

giúp mình đi

các bạn giúp mình đi

BÀI 1: \(a,1-\frac{3}{7}=\frac{4}{7}\)

BÀI 2:TÍNH

 \(a,\frac{3}{5}+\frac{5}{7}-\frac{1}{2}=\frac{46}{35}-\frac{1}{2}=\frac{57}{70}\)

\(b,\frac{1}{6}+\frac{3}{5}+\frac{2}{7}=\frac{23}{30}+\frac{2}{7}=\frac{221}{210}\)

\(c,1-\left(\frac{3}{15}+\frac{4}{5}\right)=1-\left(\frac{1}{5}+\frac{4}{5}\right)=1-1=0\)

\(d,\frac{4}{5}-\frac{3}{7}+3=\frac{13}{35}+3=\frac{118}{35}\)

HỌC TỐT ~~~

thanks nhìu !!!!!!!!!!!!!!!!!!

TÍck !!

dễ khủng khíp , động não chút đi

THÌ HÃY LÀ HỘ ĐI

máy tình làm mô ak

\(a,\frac{4}{7}+\frac{3}{5}-\frac{1}{2}=\frac{41}{35}-\frac{1}{2}=\frac{47}{70}.\)

\(b,5+\frac{1}{6}-\frac{2}{5}+\frac{3}{8}=\frac{31}{6}-\frac{2}{5}+\frac{3}{8}=\frac{143}{30}-\frac{3}{8}=\frac{527}{20}\)~~~

\(\frac{4}{7}+\frac{3}{5}-\frac{1}{2}\)

\(=\frac{47}{70}\)

\(5+\frac{1}{6}-\frac{2}{5}+\frac{3}{8}\)

\(=\frac{617}{120}\)

\(\frac{4}{7}+\frac{3}{5}-\frac{1}{2}\)

\(=\frac{40}{70}+\frac{36}{70}-\frac{35}{70}\)

\(=\frac{76}{70}-\frac{35}{70}\)

\(=\frac{41}{70}\)

b)\(5+\frac{1}{6}-\frac{2}{5}+\frac{3}{8}\)

\(=\frac{1200}{240}+\frac{40}{240}-\frac{96}{240}+\frac{90}{240}\)

\(=\frac{1200+40-96+90}{240}\)

\(=\frac{1234}{240}\)