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a) $\frac{{14}}{{18}}:\frac{8}{9} = \frac{7}{9}:\frac{8}{9} = \frac{7}{9} \times \frac{9}{8} = \frac{{63}}{{72}} = \frac{7}{8}$
b) $\frac{9}{6}:\frac{3}{{10}} = \frac{3}{2}:\frac{3}{{10}} = \frac{3}{2} \times \frac{{10}}{3} = \frac{{30}}{6} = 5$
c) $\frac{4}{5}:\frac{{10}}{{15}} = \frac{4}{5}:\frac{2}{3} = \frac{4}{5} \times \frac{3}{2} = \frac{{12}}{{10}} = \frac{6}{5}$
d) $\frac{1}{6}:\frac{{21}}{9} = \frac{1}{6}:\frac{7}{3} = \frac{1}{6} \times \frac{3}{7} = \frac{3}{{42}} = \frac{1}{{14}}$
\(1-\left(\frac{12}{5}+y=\frac{8}{9}\right):\frac{16}{9}=0\)
\(1-\left(\frac{12}{5}+y-\frac{8}{9}\right)=0\times\frac{16}{9}\)
\(1-\left(\frac{12}{5}+y-\frac{8}{9}\right)=0\)
\(\frac{12}{5}+y-\frac{8}{9}=1-0\)
\(\frac{12}{5}-y+\frac{8}{9}=1\)
\(\frac{12}{5}-y=1-\frac{8}{9}\)
\(\frac{12}{5}-y=\frac{1}{9}\)
\(y=\frac{12}{5}-\frac{1}{9}\)
\(y=\frac{108}{45}-\frac{5}{45}\)
\(y=\frac{103}{45}\)
a: Ta có:
\(\left(\dfrac{2}{5}+\dfrac{1}{5}\right)+\dfrac{1}{5}=\dfrac{3}{5}+\dfrac{1}{5}=\dfrac{4}{5}\)
\(\dfrac{2}{5}+\left(\dfrac{1}{5}+\dfrac{1}{5}\right)=\dfrac{2}{5}+\dfrac{2}{5}=\dfrac{4}{5}\)
\(\dfrac{4}{5}=\dfrac{4}{5}\). Vậy \(\left(\dfrac{2}{5}+\dfrac{1}{5}\right)+\dfrac{1}{5}=\dfrac{2}{5}+\left(\dfrac{1}{5}+\dfrac{1}{5}\right)\)
Ta có:
\(\left(\dfrac{2}{9}+\dfrac{5}{9}\right)+\dfrac{1}{9}=\dfrac{7}{9}+\dfrac{1}{9}=\dfrac{8}{9}\)
\(\dfrac{2}{9}+\left(\dfrac{5}{9}+\dfrac{1}{9}\right)=\dfrac{2}{9}+\dfrac{6}{9}=\dfrac{8}{9}\)
\(\dfrac{8}{9}=\dfrac{8}{9}\). Vậy \(\left(\dfrac{2}{9}+\dfrac{5}{9}\right)+\dfrac{1}{9}=\dfrac{2}{9}+\left(\dfrac{5}{9}+\dfrac{1}{9}\right)\)
b: \(\left(\dfrac{1}{3}+\dfrac{2}{3}\right)+\dfrac{4}{3}=\dfrac{3}{3}+\dfrac{4}{3}=\dfrac{7}{3}\)
\(\dfrac{1}{3}+\left(\dfrac{2}{3}+\dfrac{4}{3}\right)=\dfrac{1}{3}+\dfrac{6}{3}=\dfrac{7}{3}\)
\(\dfrac{7}{3}=\dfrac{7}{3}\). Vậy \(\left(\dfrac{1}{3}+\dfrac{2}{3}\right)+\dfrac{4}{3}=\dfrac{1}{3}+\left(\dfrac{2}{3}+\dfrac{4}{3}\right)\)
Đề của anh bị sai mới đúng chứ ạ? Anh Đạt ghi là \(\left(\dfrac{2}{9}+\dfrac{5}{9}\right)+\dfrac{1}{9}\) chứ có phải \(\dfrac{2}{5}\) đâu ạ?
M = (345 x (6789 + 3456 - 245)/690) x 99/100 x 98/99 x...x 2/3 x 1/2
M = ((345 x 10000)/690) x 99/2 (rút gọn)
M = (10000/2) x 99/2
M = 5000 x 99/2
M = 247500
Ok nha
Tổng của 3 phân số là:
(23/20+7/20+21/20):2=37/10
Phân số thứ nhất là:
37/10-7/20=67/20
Phân số thứ hai là:
37/10-21/20=53/20
Phân số thứ ba là:
37/10-23/20=51/20
Đáp số : phân số thứ 1:67/20
phân số thứ 2
phân số thứ 3
Đáp số: phân số thứ 1 : 67/20
phân số thứ 2 : 53/20
phân số thứ 3 : 51/20
Chúc bạn học giỏi!
60x [7/12+4/15]
60x153/180
=9180/180
b 1/2x2/3x3/4x4/5x5/6x6/7x7/8x8/9=40320/4032
Bài 2:
a: C1: \(\dfrac{7}{5}+\dfrac{9}{7}+\dfrac{6}{5}+\dfrac{11}{7}\)
\(=\left(\dfrac{7}{5}+\dfrac{6}{5}\right)+\left(\dfrac{11}{7}+\dfrac{9}{7}\right)\)
\(=\dfrac{13}{5}+\dfrac{20}{7}=\dfrac{91+100}{35}=\dfrac{191}{35}\)
C2: \(\dfrac{7}{5}+\dfrac{9}{7}+\dfrac{6}{5}+\dfrac{11}{7}\)
\(=\dfrac{49}{35}+\dfrac{45}{35}+\dfrac{42}{35}+\dfrac{55}{35}\)
\(=\dfrac{49+45+42+55}{35}=\dfrac{191}{35}\)
b: C1: \(\dfrac{8}{11}+\dfrac{2}{11}+\dfrac{12}{12}+\dfrac{31}{11}\)
\(=\left(\dfrac{8}{11}+\dfrac{2}{11}+\dfrac{31}{11}\right)+1\)
\(=\dfrac{41}{11}+1=\dfrac{52}{11}\)
C2: \(\dfrac{8}{11}+\dfrac{2}{11}+\dfrac{12}{12}+\dfrac{31}{11}\)
\(=\dfrac{96}{132}+\dfrac{24}{132}+\dfrac{132}{132}+\dfrac{372}{132}\)
\(=\dfrac{96+24+132+372}{132}=\dfrac{624}{132}=\dfrac{52}{11}\)
Bài 1:
a: \(\left(\dfrac{4}{5}+\dfrac{2}{3}\right)\times\dfrac{1}{6}=\dfrac{12+10}{15}\times\dfrac{1}{6}\)
\(=\dfrac{22}{90}=\dfrac{11}{45}\)
b: \(\left(\dfrac{7}{8}-\dfrac{4}{16}\right)\times\dfrac{2}{3}=\left(\dfrac{14}{16}-\dfrac{4}{16}\right)\times\dfrac{2}{3}\)
\(=\dfrac{10}{16}\times\dfrac{2}{3}=\dfrac{5}{8}\times\dfrac{2}{3}=\dfrac{5}{12}\)
c: \(\dfrac{5}{9}\times\dfrac{2}{4}+\dfrac{4}{6}\times\dfrac{2}{4}\)
\(=\dfrac{2}{4}\left(\dfrac{5}{9}+\dfrac{2}{3}\right)\)
\(=\dfrac{1}{2}\times\dfrac{5+6}{9}=\dfrac{1}{2}\times\dfrac{11}{9}=\dfrac{11}{18}\)
d: \(\dfrac{15}{3}\times\dfrac{2}{6}-\dfrac{11}{7}\times\dfrac{2}{6}\)
\(=\dfrac{2}{6}\times\left(\dfrac{15}{3}-\dfrac{11}{7}\right)\)
\(=\dfrac{1}{3}\times\left(5-\dfrac{11}{7}\right)=\dfrac{1}{3}\times\dfrac{24}{7}=\dfrac{8}{7}\)