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Tính hợp lí:
a) \(\left(-0,4\right)+\dfrac{3}{8}+\left(-0,6\right)\)
\(=\left[\left(-0,4\right)+\left(-0,6\right)\right]+\dfrac{3}{8}\)
\(=-1+\dfrac{3}{8}\)
\(=\dfrac{\left(-8\right)+3}{8}\)
\(=\dfrac{-5}{8}\)
b) \(\dfrac{4}{5}-1,8+0,375+\dfrac{5}{8}\)
\(=\dfrac{4}{5}-\dfrac{9}{5}+\dfrac{3}{8}+\dfrac{5}{8}\)
\(=-1+1\)
\(=0\\\)
c) \(\dfrac{7}{3}.\left(-2,5\right).\dfrac{6}{7}\)
\(=\dfrac{7}{3}.\dfrac{-5}{2}.\dfrac{6}{7}\)
\(=\dfrac{7}{3}.\dfrac{6}{7}.\dfrac{-5}{2}\)
\(=2.\dfrac{-5}{2}\)
\(=-5\)
d) \(\dfrac{7}{12}.\left(-2,34\right)-\dfrac{7}{12}.\left(-0,34\right)\)
\(=\dfrac{7}{12}.\left[\left(-2,34\right)+0,34\right]\)
\(=\dfrac{7}{12}.\left(-2\right)\)
\(=\dfrac{-7}{6}\)
e) \(\dfrac{-8}{3}.\dfrac{2}{11}-\dfrac{8}{3}:\dfrac{11}{9}\)
\(=\dfrac{8}{3}.\dfrac{-2}{11}-\dfrac{8}{3}.\dfrac{9}{11}\)
\(=\dfrac{8}{3}.\left(\dfrac{-2}{11}-\dfrac{9}{11}\right)\)
\(=\dfrac{8}{3}.-1\)
\(=\dfrac{-8}{3}\)
Chúc bạn học tốt
\(4\dfrac{3}{4}+\left(-0,37\right)+\dfrac{1}{8}+\left(-1,28\right)+\left(-2,5\right)+3\dfrac{1}{12}\)
\(=\dfrac{19}{4}+-\dfrac{37}{100}+\dfrac{1}{8}+-\dfrac{32}{25}+-\dfrac{5}{2}+\dfrac{37}{12}\)
\(=\dfrac{219}{50}+\dfrac{1}{8}+-\dfrac{32}{25}+-\dfrac{5}{2}+\dfrac{37}{12}\)
\(=\dfrac{901}{200}+-\dfrac{32}{25}+-\dfrac{5}{2}+\dfrac{37}{12}\)
\(=\dfrac{129}{40}+-\dfrac{5}{2}+\dfrac{37}{12}\)
\(=\dfrac{29}{40}+\dfrac{37}{12}\)
\(=\dfrac{457}{120}\)
Nhớ ủng hộ 1 Đúng !
=19/4-37/100+1/8-32/25-5/2+37/12
=(38/8+1/8-20/8)-(37/100+128/100)+37/12
=19/8-155/100+37/12
=469/120
1. Tính hợp lí
a) \(0,7+\dfrac{-7}{19}-\left(-0,3\right)\)
\(=\dfrac{7}{10}+\dfrac{-7}{19}+\dfrac{3}{10}\)
\(=\left(\dfrac{7}{10}+\dfrac{3}{10}\right)+\dfrac{-7}{19}\)
\(=1+\dfrac{-7}{19}\)
\(=\dfrac{12}{19}\)
b) \(\dfrac{5}{3}.\left(-2,5\right):\dfrac{5}{6}\)
\(=\dfrac{5}{3}.\dfrac{-5}{2}.\dfrac{6}{5}\)
\(=\left(\dfrac{5}{3}.\dfrac{6}{5}\right).\dfrac{-5}{2}\)
\(=2.\dfrac{-5}{2}\)
\(=-5\)
c) \(0,6.\dfrac{-5}{17}-\dfrac{3}{5}.\dfrac{12}{17}\)
\(=\dfrac{3}{5}.\dfrac{-5}{17}-\dfrac{3}{5}.\dfrac{12}{17}\)
\(=\dfrac{3}{5}.\left(\dfrac{-5}{17}-\dfrac{12}{17}\right)\)
\(=\dfrac{3}{5}.-1\)
\(=\dfrac{-3}{5}\)
d) \(\dfrac{7}{4}.\dfrac{5}{2}-\dfrac{7}{4}.\dfrac{3}{2}\)
\(=\dfrac{7}{4}.\left(\dfrac{5}{2}-\dfrac{3}{2}\right)\)
\(=\dfrac{7}{4}.1\)
\(=\dfrac{7}{4}\)
Chúc bạn học tốt
a: \(A=\dfrac{7}{12}+\dfrac{5}{72}-\dfrac{11}{36}=\dfrac{42}{72}+\dfrac{5}{72}-\dfrac{22}{72}=\dfrac{25}{72}\)
b: \(B=\dfrac{8+5}{10}:\dfrac{-5}{13}=\dfrac{13}{10}\cdot\dfrac{13}{-5}=-\dfrac{169}{100}\)
c: \(C=\left(\dfrac{88}{132}-\dfrac{33}{132}+\dfrac{60}{132}\right):\left(\dfrac{55}{132}+\dfrac{132}{132}-\dfrac{84}{132}\right)\)
\(=\dfrac{88-33+60}{55+132-84}=\dfrac{115}{103}\)
\(A=\left(3-\dfrac{1}{4}+\dfrac{3}{2}\right)-\left(5+\dfrac{1}{3}-\dfrac{5}{6}\right)-\left(6-\dfrac{7}{4}+\dfrac{2}{3}\right)\\ \Rightarrow A=3-\dfrac{1}{4}+\dfrac{3}{2}-5-\dfrac{1}{3}+\dfrac{5}{6}-6+\dfrac{7}{4}-\dfrac{2}{3}\\ \Rightarrow A=\left(3-5-6\right)-\left(\dfrac{1}{4}+\dfrac{7}{4}\right)+\left(\dfrac{3}{2}+\dfrac{5}{6}-\dfrac{2}{3}\right)\\ \Rightarrow A=-8-\dfrac{3}{2}+\dfrac{5}{3}\\ =-\dfrac{47}{6}.\\ B=0,5+\dfrac{1}{3}+0,4+\dfrac{5}{7}+\dfrac{1}{6}-\dfrac{4}{35}+\dfrac{1}{41}\)
\(\Rightarrow B=\left(0,5+0,4\right)+\left(\dfrac{1}{3}+\dfrac{1}{6}\right)+\left(\dfrac{5}{7}-\dfrac{4}{35}\right)+\dfrac{1}{41}\\ \Rightarrow B=\dfrac{9}{10}+\dfrac{1}{2}+\dfrac{3}{5}+\dfrac{1}{41}\\ \Rightarrow B=2+\dfrac{1}{41}\\ \Rightarrow B=\dfrac{83}{41}.\)
