Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
bài 1 :
a) \(\frac{8}{10}-\frac{9}{12}+\frac{15}{18}-\frac{12}{14}=\frac{4}{5}-\frac{3}{4}+\frac{5}{6}-\frac{6}{7}=\frac{16}{20}-\frac{15}{20}+\frac{35}{42}-\frac{36}{42}=\frac{1}{20}-\frac{1}{42}=\frac{11}{420}\)
b) \(\frac{5}{7}.\frac{5}{11}+\frac{5}{7}.\frac{2}{11}-\frac{5}{7}.\frac{14}{11}=\frac{5}{7}\left(\frac{5}{11}+\frac{2}{11}-\frac{14}{11}\right)=\frac{5}{7}.-\frac{7}{11}=-\frac{5}{11}\)
1, a, \(\frac{8}{10}-\frac{9}{12}+\frac{15}{18}-\frac{12}{14}=\frac{4}{5}-\frac{3}{4}+\frac{5}{6}-\frac{6}{7}=\frac{11}{420}\) (tính máy tính thôi)
b, \(\frac{5}{7}.\frac{5}{11}+\frac{5}{7}.\frac{2}{11}-\frac{5}{7}.\frac{14}{11}=\frac{5}{7}\left(\frac{5}{11}+\frac{2}{11}-\frac{14}{11}\right)=\frac{5}{7}.\frac{-7}{11}=-\frac{5}{11}\)
2, a, Số cần tìm là:
\(7,2:\frac{2}{3}=10,8\)
b, Số cần tìm là:
\(-5:\frac{10}{7}=-\frac{7}{2}\)
e, \(\frac{3}{14}:\frac{1}{28}-\frac{13}{21}:\frac{1}{28}+\frac{28}{42}:\frac{1}{28}-8\)
\(=\left(\frac{3}{14}-\frac{13}{21}+\frac{2}{3}\right):\frac{1}{28}-8\)
\(=\frac{11}{42}:\frac{1}{28}-8\)
\(=\frac{22}{3}-8\)
\(=-\frac{2}{3}\)
e, \(\frac{3}{14}:\frac{1}{28}-\frac{13}{21}:\frac{1}{28}+\frac{28}{42}:\frac{1}{28}-8\)
\(=\left(\frac{3}{14}-\frac{13}{21}+\frac{2}{3}\right):\frac{1}{28}-8\)
\(=\frac{11}{42}:\frac{1}{28}-8\)
\(=\frac{22}{3}-8\)
\(=-\frac{2}{3}\)
- \(\frac{11}{125}-\frac{17}{18}-\frac{5}{7}+\frac{4}{9}+\frac{17}{14}\)
\(=\left(-\frac{17}{18}+\frac{4}{9}\right)+\left(-\frac{5}{7}+\frac{17}{14}\right)+\frac{11}{125}\)
\(=-1+\frac{1}{2}+\frac{11}{125}\)
\(=-1+\frac{147}{125}\)
\(=\frac{22}{125}\)
2. \(1-\frac{1}{2}+2-\frac{2}{3}+3-\frac{3}{4}+4-\frac{1}{4}-3-\frac{1}{3}-2-\frac{1}{2}-1\)
\(=\left(1+2+3+4-3-2-1\right)\)\(+\left(-\frac{1}{2}-\frac{1}{2}\right)+\left(-\frac{2}{3}-\frac{1}{3}\right)+\left(-\frac{3}{4}-\frac{1}{4}\right)\)
\(=4-1-1-1\)
\(=1\)
a ) \(\left(-\frac{40}{52}.0,32.\frac{17}{20}\right):\frac{64}{75}\)
= \(\left(-\frac{16}{65}.\frac{17}{20}\right):\frac{64}{75}\)
= \(\left(-\frac{68}{325}\right):\frac{64}{75}\)
= \(\frac{-51}{208}\)
b ) \(-\frac{10}{11}.\frac{8}{9}+\frac{7}{18}.\frac{10}{11}\)
= \(\frac{10}{11}.\left(-\frac{8}{9}+\frac{7}{18}\right)\)
= \(\frac{10}{11}.\left(-\frac{1}{2}\right)\)
= \(\frac{-5}{11}\)
c ) \(\frac{45^{10}.5^{20}}{75^{15}}\)
= \(\frac{5^{10}.3^{20}.5^{20}}{5^{30}.3^{15}}\)
= \(\frac{5^{30}.3^{20}}{5^{30}.3^{15}}\)
= 3 5
= 243
d ) ( - 0,125 ) 3 . 80 4
= -80000
Bài làm :
a)\(=-\frac{3}{5}+\frac{28}{5}\times\frac{9}{14}=-\frac{3}{5}+\frac{18}{5}=3\)
b)\(=\frac{55}{126}+\frac{5}{42}+\frac{4}{9}=1\)
c)\(=-\frac{51}{13}-\frac{27}{13}=-6\)
d)\(=\frac{7}{3}-11\frac{1}{4}\times\frac{2}{15}=\frac{7}{3}-\frac{3}{2}=\frac{5}{6}\)
e)\(=1\times\frac{8}{3}\times0,25=\frac{2}{3}\)
Ta có :
(7/18 + 11/18 + a/b) : 3 = a/b
=> 18/18 + a/b = 3 . a/b
=> 1 = 3 . a/b - a/b
=> 2 . a/b = 1
=> a/b = 1 : 2 = 1/2
Vậy phân số a/b cần tìm là 1/2.