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\(a,(\frac{1}{4}+\frac{-5}{13})+(\frac{2}{11}+\frac{-8}{13}+\frac{3}{4})\)
\(= (\frac{1}{4} + \frac{3}{4}) + (\frac{-5}{13} + \frac{-8}{13}) + \frac{2}{11}\)
\(= \frac{4}{4} + \frac{-13}{13} + \frac{2}{11}\)
\(=1+(-1)+\frac{2}{11}=\frac{2}{11}\)
\(b,(\frac{21}{31}+\frac{-16}{7})+(\frac{44}{53}+\frac{10}{31})+\frac{9}{53}\)
\(= (\frac{21}{31} + \frac{10}{31}) + (\frac{44}{53} + \frac{9}{53}) + \frac{-16}{7}\)
\(=\frac{31}{31}+\frac{53}{53}+\frac{-16}{7}=1+1-\frac{16}{7}\)
\(=2-\frac{16}{7}=\frac{14}{7}-\frac{16}{7}=-\frac27\)
\(c,\frac{-5}{7}+\frac{3}{4}+\frac{-1}{5}+\frac{-2}{7}+\frac{1}{4}\)
\(= (\frac{-5}{7} + \frac{-2}{7}) + (\frac{3}{4} + \frac{1}{4}) + \frac{-1}{5}\)
\(= \frac{-7}{7} + \frac{4}{4} + \frac{-1}{5}\)
\(=-1+1-\frac{1}{5}=0-\frac15=-\frac15\)
\(\frac{-3}{31} + \frac{-6}{17} + \frac{1}{25} + \frac{-28}{31} + \frac{-11}{17} + \frac{-1}{5}\)
\(= (\frac{-3}{31} + \frac{-28}{31}) + (\frac{-6}{17} + \frac{-11}{17}) + \frac{1}{25} + \frac{-1}{5}\)
\(= \frac{-31}{31} + \frac{-17}{17} + \frac{1}{25} - \frac{5}{25}\)
\(= -1 + (-1) + \frac{-4}{25}\)
\(=-2-\frac{4}{25}=-\frac{50}{25}-\frac{4}{25}=-\frac{54}{25}\)
Bài này mình sẽ giảng thôi, tại nó cũng khá dễ ạ
Câu A: Bạn phá ngoặc, đổi dấu + trong ngoặc thành -, lấy cái thứ nhất - cái thứ 3 , ra kết quả thì - cái thứ 2 (Bạn tự quy đồng ...)
Câu B: Bạn lấy 5/9 làm thừa số chung và cho 7/13 + 9/13 - 3/13 vào trong ngoặc, tính ra được cái trong ngoặc rồi lấy 5/9 x với kết quả vừa tính được
Bài 2:
- \(\frac75\) + \(x\) = - \(\frac34\)
\(x\) = - \(\frac34+\frac75\)
\(x=-\frac{15}{20}\) + \(\frac{28}{20}\)
\(x\) = \(\frac{13}{20}\)
Vậy \(x=\frac{13}{20}\)
Bài 3:
- \(\frac74\) + \(\frac14:x\) = \(\frac32\)
\(\frac14:x\) = \(\frac32+\frac74\)
\(\frac14:x\) = \(\frac64+\frac74\)
\(\frac14:x=\frac{13}{4}\)
\(x=\frac14:\frac{13}{4}\)
\(x=\frac14\times\frac{4}{13}\)
\(x=\frac{1}{13}\)
Vậy \(x=\frac{1}{13}\)
Bài làm
a) \(-\frac{3}{7}+\frac{3}{4}:\frac{3}{14}\)
= \(-\frac{3}{7}+\frac{3}{4}.\frac{14}{3}\)
= \(-\frac{3}{7}+\frac{7}{2}\)
\(=-\frac{7}{14}+\frac{49}{14}\)
\(=\frac{42}{14}=3\)
b) \(5-\frac{7}{39}:\frac{7}{13}+\frac{8}{9}:4\)
\(=5=\frac{7}{39}.\frac{13}{7}+\frac{8}{9}.\frac{1}{4}\)
\(=5-\frac{1}{3}+\frac{2}{9}\)
\(=\frac{45}{9}-\frac{3}{9}+\frac{2}{9}\)
\(=\frac{44}{9}\)
c) \(\left(\frac{5}{12}:\frac{11}{6}+\frac{5}{12}:\frac{11}{5}\right)-\frac{-7}{12}\)
\(=\left(\frac{5}{12}.\frac{6}{11}+\frac{5}{12}.\frac{5}{11}\right)+\frac{7}{12}\)
\(=\left[\frac{5}{12}\left(\frac{6}{11}+\frac{5}{11}\right)\right]+\frac{7}{12}\)
\(=\frac{5}{12}+\frac{7}{12}\)
\(=\frac{12}{12}=1\)
d) \(-\frac{5}{9}+\frac{14}{9}\left(\frac{3}{4}-\frac{2}{5}\right):49\)
\(=-\frac{5}{9}+\frac{14}{9}\left(\frac{15}{20}-\frac{8}{20}\right):49\)
\(=-\frac{5}{9}+\frac{14}{9}.\frac{7}{20}.\frac{1}{49}\)
\(=-\frac{5}{9}+\frac{7}{9}.\frac{7}{10}.\frac{1}{7.7}\)
\(=-\frac{5}{9}+\frac{1}{90}\)
\(=-\frac{50}{90}+\frac{1}{90}=-\frac{49}{90}\)
a) \(\frac{1}{3}.\frac{-6}{13}.\frac{-9}{10}.\frac{-13}{36}\)
\(=\left(\frac{1}{3}.\frac{-9}{10}\right)\left(\frac{-6}{13}.\frac{-13}{36}\right)\)
\(=\frac{-3}{10}.\frac{1}{6}\)
\(=\frac{-1}{20}\)
b) \(\frac{-1}{3}.\frac{-15}{17}.\frac{34}{45}\)
\(=\frac{-1}{3}.\frac{-2}{3}\)
\(=\frac{2}{9}\)
c) \(\left(1-\frac{1}{5}\right)\left(\frac{-3}{10}+\frac{1}{5}\right)\)
\(=\frac{4}{5}.\frac{-1}{10}\)
\(=\frac{-2}{25}\)
d) \(A=\frac{1}{3}.\frac{4}{5}+\frac{1}{3}.\frac{6}{5}+\frac{2}{3}\)
\(=\frac{1}{3}\left(\frac{4}{5}+\frac{6}{5}\right)+\frac{2}{3}\)
\(=\frac{1}{3}.2+\frac{2}{3}\)
\(=\frac{2}{3}+\frac{2}{3}\)
\(=\frac{4}{3}\)
e) \(11\frac{1}{4}-\left(2\frac{5}{7}+5\frac{1}{4}\right)\)
\(=\left(11\frac{1}{4}-5\frac{1}{4}\right)-2\frac{5}{7}\)
\(=6-2\frac{5}{7}\)
\(=5\frac{7}{7}-2\frac{5}{7}\)
\(=3\frac{2}{7}\)
Câu a:
(1/4 + -5/13) + (2/11 + -8/13 + 3/4)
= 1/4 - 5/13 + 2/11 - 8/13 + 3/4
= (1/4 + 3/4) - (5/13+ 8/13) + 2/11
= 1 - 1 + 2/11
= 0 + 2/11
= 2/11
Câu b:
Câu b:
(21/31 + -16/7) + (44/53 + 10/31) + 9/53
= 21/31 - 16/7 + 44/53 + 10/31 + 9/53
= (21/31 + 10/31) + (44/53 + 9/53) - 16/7
= 1 + 1 - 16/7
= 2 - 16/7
= -2/7
\(\frac27\times5\frac14-\frac27\times3\frac14\)
=\(\frac27\times\left(5\frac14-3\frac14\right)\)
=\(\frac27\times\left(\left(5-3\right)+\left(\frac14-\frac15\right)\right)\)
=\(\frac27\times\left(2+0\right)\)
=\(\frac27\times2\)
=\(\frac47\)
\(11\frac{3}{13}-\left(2\frac{4}{7}+5\frac{3}{13}\right)\)
\(=11\frac{3}{13}-2\frac{4}{7}-5\frac{3}{13}\)
\(=11+\frac{3}{13}-2-\frac{4}{7}-5-\frac{3}{13}\)
\(=\left(11-2-5\right)+\left(\frac{3}{13}-\frac{3}{13}\right)-\frac{4}{7}\)
\(=4+\frac{4}{7}\)
\(=4\frac{4}{7}\)
hok tốt
\(11\frac{3}{13}-\left(1\frac{4}{7}+5\frac{3}{13}\right)\)
\(=\frac{146}{13}-\left(\frac{11}{7}+\frac{68}{13}\right)\)
\(=\left(\frac{146}{13}-\frac{68}{13}\right)+\frac{11}{7}\)
\(=6+\frac{11}{7}\)
\(=\frac{53}{7}\)
Học tốt #
\(11\frac{3}{13}-\left(2\frac{4}{7}+5\frac{3}{13}\right)\)
\(=11\frac{3}{13}-2\frac{4}{7}-5\frac{3}{13}\)
\(=\left(11\frac{3}{13}-5\frac{3}{13}\right)-2\frac{4}{7}\)
\(=\left(\frac{146}{13}-\frac{68}{13}\right)-\frac{18}{7}\)
\(=\frac{78}{13}-\frac{18}{7}\)
\(=6-2\frac{4}{7}\)
\(=4\frac{4}{7}\)
\(11\frac{3}{13}-\left(2\frac{4}{7}+5\frac{3}{13}\right)\)
\(=11\frac{3}{13}-2\frac{4}{7}-5\frac{3}{13}\)
\(=11+\frac{3}{13}-2-\frac{4}{7}-5-\frac{3}{13}\)
\(=\left(11-2-5\right)+\left(\frac{3}{13}-\frac{3}{13}\right)-\frac{4}{7}\)
\(=4-\frac{4}{7}=\frac{24}{7}\)
11\(\frac{3}{13}\)-( 2\(\frac{4}{7}\)+ 5\(\frac{3}{13}\)).
= \(\frac{146}{13}\)- \(\frac{18}{7}\)- \(\frac{68}{13}\).
=( \(\frac{146}{13}\)- \(\frac{68}{13}\))- \(\frac{18}{7}\).
= 6- \(\frac{18}{7}\).
= \(\frac{42}{7}\)- \(\frac{18}{7}\).
= \(\frac{24}{7}\).