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a,\(\frac{7}{10}\cdot\frac{4}{9}+\frac{3}{10}\cdot\frac{4}{9}-1\frac{7}{9}\)
\(=\frac{14}{45}+\frac{2}{15}-\frac{16}{9}\)
\(=\frac{14}{45}+\frac{6}{45}-\frac{80}{45}\)
\(=\frac{-60}{45}=\frac{-4}{3}\)
b,\(\frac{-5}{6}+\frac{4}{9}\cdot\left(\frac{5}{4}-\frac{2}{3}\right)\cdot\left(-3\right)^2+\frac{5}{9}\cdot30\%\)
\(=\frac{-5}{6}+\frac{4}{9}\cdot\left(\frac{7}{12}\right)\cdot9+\frac{5}{9}\cdot\frac{3}{10}\)
\(=\frac{-5}{6}+\frac{7}{3}+\frac{1}{6}\)
\(=\frac{-5}{6}+\frac{14}{6}+\frac{1}{6}\)
=\(=\frac{10}{6}=\frac{5}{3}\)
a, 13/6+5/8 : -3/4 - 7/12.4
= 13/6 + -5/6-7/3
=8/6-7/3
= -6/6
= -1
b, ( 73/5 - 21/3) + ( 4/3-43/5 )
= 73/5-21/3+4/3-43/5
=( 73/5-43/5)-(21/3-4/3)
= 6-17/3
=1/3
c, 7/5.4/9 +7/5: 9/16- 14/10.2/9
= 7/5.4/9 +7/5.16/9 - 14/45
=7/5.(4/9+16/9)-14/45
=7/5.20/9-14/45
= 140/45 - 14/45
= 126/45
Xong rùi nè! Nhưng bạn kiểm tra lại giùm nhé vì làm vào ban đêm nên hơi bất tiện
#)Trả lời :
a) \(\frac{-1}{2}+\frac{2}{7}-\frac{5}{28}\)
\(=\frac{-3}{14}-\frac{5}{28}\)
\(=\frac{-11}{28}\)
b) \(5\frac{3}{4}+\left(\frac{1}{9}-1\frac{3}{4}\right)\)
\(=\left(5\frac{3}{4}-1\frac{3}{4}\right)+\frac{1}{9}\)
\(=4+\frac{1}{9}\)
\(=4\frac{1}{9}=\frac{37}{9}\)
c) \(\frac{-5}{7}x\frac{2}{11}+\frac{-5}{7}x\frac{9}{11}+3\frac{5}{7}\)
\(=\frac{-5}{7}x\left(\frac{2}{11}+\frac{9}{11}\right)+3\frac{5}{7}\)
\(=\frac{-5}{7}x1+3\frac{5}{7}\)
\(=\frac{-5}{7}+3\frac{5}{7}\)
\(=\frac{-5}{7}+\frac{26}{7}\)
\(=\frac{21}{7}=3\)
#~Will~be~Pens~#
Câu a )
\(-\frac{3}{5}+\frac{9}{16}+-\frac{2}{5}+\frac{7}{16}=\left(-\frac{3}{5}+-\frac{2}{5}\right)+\left(\frac{9}{16}+\frac{7}{16}\right).\)
\(=\left(-1\right)+1=0\)
hk tốt !
Bài 2:
Ta thấy: 52 > 4.5
62 > 5.6
72 > 6.7
....
20172 > 2016.2017
\(\Rightarrow\)\(\frac{1}{5^2}< \frac{1}{4.5}\)
\(\frac{1}{6^2}< \frac{1}{5.6}\)
\(\frac{1}{7^2}< \frac{1}{6.7}\)
....
\(\frac{1}{2017^2}< \frac{1}{2016.2017}\)
Cộng vế với nhau, ta có:
\(\frac{1}{5^2}+\frac{1}{6^2}+\frac{1}{7^2}+...+\frac{1}{2017^2}\) < \(\frac{1}{4.5}+\frac{1}{5.6}+\frac{1}{6.7}+...+\frac{1}{2016.2017}\)
\(\Rightarrow\)A < \(\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}+\frac{1}{6}-\frac{1}{7}+...+\frac{1}{2016}-\frac{1}{2017}\)
\(\Rightarrow\)A < \(\frac{1}{4}-\frac{1}{2017}\)
\(\Rightarrow\)A < \(\frac{1}{4}\)( vì \(\frac{1}{2017}>0\))
k giúp mik ✅
