tính nhanh
\(\frac{-5}{21}\)+ \(\frac{-2}{21}\)+ \(\frac{8}{24}\)
K
Khách
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27 tháng 4 2020
a)\(\frac{5}{12}+1-\frac{3}{7}+\frac{2}{24}-\frac{8}{14}\)
\(=\frac{5}{12}+1-\frac{3}{7}+\frac{1}{12}-\frac{4}{7}\)
\(=\left(\frac{5}{12}+\frac{1}{12}\right)+1-\left(\frac{3}{7}+\frac{4}{7}\right)\)
\(=\frac{1}{2}+1-1=\frac{1}{2}\)
b)\(-\frac{23}{4}+\frac{1}{2}+\frac{21}{4}-2\)
\(=\left(-\frac{23}{4}+\frac{21}{4}+\frac{2}{4}\right)-2\)
\(=-2\)
VP
3
LL
26 tháng 4 2018
\(\frac{5}{11}+3\frac{8}{21}+\frac{6}{11}-\frac{8}{21}\)
\(=\frac{5}{11}+\frac{71}{21}+\frac{6}{11}-\frac{8}{21}\)
\(=\left(\frac{5}{11}+\frac{6}{11}\right)+\left(\frac{71}{21}-\frac{8}{21}\right)\)
\(=1+3\)
\(=4\)
Đúng lun, Mn tk mk nha!
26 tháng 4 2018
\(\frac{5}{11}+3\frac{8}{21}+\frac{6}{11}-\frac{8}{21}\)
=\(\frac{5}{11}+\frac{71}{21}+\frac{6}{11}-\frac{8}{21}\)
=\(\left(\frac{5}{11}+\frac{6}{11}\right)+\left(\frac{71}{21}-\frac{8}{21}\right)\)
=\(1+3\)
=
S
10 tháng 3 2019
\(a,=\left(-\frac{3}{7}+\frac{3}{7}\right)+\frac{5}{13}=0+\frac{5}{13}=\frac{5}{13}\)
\(b,=-\frac{5}{21}+\left(-\frac{2}{21}\right)+\frac{8}{24}=-\frac{1}{3}+\frac{1}{3}=0\)
\(c,=\left[-\frac{6}{11}+\frac{\left(-5\right)}{11}\right]+2=-1+2=1\)
\(d,=\frac{-1+\left(-15\right)}{32}+\frac{1}{2}=-\frac{1}{2}+\frac{1}{2}=0\)
10 tháng 3 2019
a) \(\frac{-3}{7}+\frac{5}{13}+\frac{3}{7}\)
\(=\left(\frac{-3}{7}+\frac{3}{7}\right)+\frac{5}{13}\)
\(=0+\frac{5}{13}=\frac{5}{13}\)
b) \(\frac{-5}{21}+\frac{-2}{21}+\frac{8}{24}\)
\(=\frac{-7}{21}+\frac{1}{3}\)
\(=\frac{-1}{3}+\frac{1}{3}=0\)
c) \(\frac{-5}{11}+\left(\frac{-6}{11}+2\right)\)
\(=\frac{-5}{11}+\frac{-6}{11}+2\)
\(=\left(-1\right)+2=1\)
d) \(\left(\frac{-1}{32}+\frac{1}{2}\right)+\frac{-15}{32}\)
\(=\frac{-1}{32}+\frac{1}{2}+\frac{-15}{32}\)
\(=\left(\frac{-1}{32}+\frac{-15}{32}\right)+\frac{1}{2}\)
\(=\frac{-16}{32}+\frac{1}{2}\)
\(=\frac{-1}{2}+\frac{1}{2}=0\)
NQ
2
1 tháng 4 2019
\(\left(\frac{136}{15}-\frac{28}{5}+\frac{62}{10}\right).\frac{21}{24}\)
\(=\left(\frac{136}{15}-\frac{28}{5}+\frac{31}{5}\right).\frac{21}{24}\)
\(=\left[\frac{136}{15}-\left(\frac{28}{5}-\frac{31}{5}\right)\right].\frac{21}{24}\)
\(=\left(\frac{136}{15}+\frac{3}{5}\right).\frac{21}{24}\)
\(=\frac{29}{3}.\frac{21}{24}\)
\(=\frac{203}{24}\)
Study well ! >_<
6 tháng 9 2018
a) -90/189 + 45/84 - 78/126
= -10/21 + 15/28 - 13/21
= (-10/21 - 13/21) + 15/28
= -24/21 + 15/28
= -17/28
24 tháng 11 2016
\(\left(5-\frac{2}{3}+\frac{3}{7}\right):\left(24-25+\frac{4}{21}-\frac{8}{21}\right)\)
\(\left(\frac{5.21-14+9}{21}\right):\left(\frac{-21-4}{21}\right)\)=\(\left(\frac{5.21-5}{21}\right).\left(\frac{21}{-25}\right)\)=\(\frac{5\left(21-1\right)}{\left(-5\right).5}=\frac{20}{-5}\)
=-4
= \(\frac{-7}{21}+\frac{8}{24}=0\)