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Giải:
Đặt \(A=13\frac{1}{4}-2\frac{5}{27}-10\frac{5}{6},B=1\frac{3}{7}+\frac{10}{3},C=12\frac{1}{3}-14\frac{2}{7}\)
Ta có:
\(A=13-2-10+\frac{1}{4}-\frac{5}{27}-\frac{5}{6}=1+\frac{27-20-90}{108}=1-\frac{83}{108}=\frac{25}{108}\)
\(A.230\frac{1}{5}=\frac{25}{108}.230\frac{1}{25}=\frac{25}{108}.\frac{5751}{25}=\frac{5751}{108}=\frac{213}{4}\)
\(A.230\frac{1}{25}+46\frac{3}{4}=\frac{213}{4}+\frac{187}{4}=100\)
\(B=1+\frac{3}{7}+3+\frac{1}{3}=4+\frac{3}{7}+\frac{1}{3}=4+\frac{16}{21}=\frac{100}{21}\)
\(C=12\frac{1}{3}-14\frac{2}{7}=12-14+\frac{1}{3}-\frac{2}{7}=-2+\frac{7-6}{21}=-\frac{41}{21}\)
\(B:C=\frac{100}{21}:\left(-\frac{41}{21}\right)=-\frac{100}{41}\)
\(E=\frac{A.230\frac{1}{25}+46\frac{3}{4}}{B:C}=\frac{100}{-\frac{100}{41}}=-41\)
\(\frac{\left(13\frac{1}{4}-2\frac{5}{7}-10\frac{5}{6}\right).230\frac{1}{25}+46\frac{3}{4}}{\left(1\frac{3}{10}+\frac{10}{3}\right):\left(12\frac{1}{3}-14\frac{2}{7}\right)}=\frac{\left(\frac{53}{4}-\frac{19}{7}-\frac{65}{6}\right).\frac{5751}{25}+\frac{187}{4}}{\left(\frac{13}{10}+\frac{10}{3}\right):\left(\frac{37}{3}-\frac{100}{7}\right)}\)
\(=\frac{\left(\frac{1113}{84}-\frac{228}{84}-\frac{910}{84}\right).\frac{5751}{25}+\frac{187}{4}}{\left(\frac{39}{30}+\frac{100}{30}\right):\left(\frac{259}{21}-\frac{300}{21}\right)}\)
\(=\frac{\frac{-25}{84}.\frac{5751}{25}+\frac{187}{4}}{\frac{139}{30}:\frac{-41}{21}}\)
\(=\frac{\frac{-1917}{28}+\frac{1309}{28}}{\frac{139}{30}.\frac{-21}{41}}\)
\(=\frac{\frac{-608}{28}}{\frac{-973}{410}}=\frac{-152}{7}.\frac{410}{-973}=\frac{62320}{6811}\)
1
Ez lắm =)
Bài 1:
Với mọi gt \(x,y\in Q\) ta luôn có:
\(x\le\left|x\right|\) và \(-x\le\left|x\right|\)
\(y\le\left|y\right|\) và \(-y\le\left|y\right|\Rightarrow x+y\le\left|x\right|+\left|y\right|\) và \(-x-y\le\left|x\right|+\left|y\right|\)
Hay: \(x+y\ge-\left(\left|x\right|+\left|y\right|\right)\)
Do đó: \(-\left(\left|x\right|+\left|y\right|\right)\le x+y\le\left|x\right|+\left|y\right|\)
Vậy: \(\left|x+y\right|\le\left|x\right|+\left|y\right|\)
Dấu "=" xảy ra khi: \(xy\ge0\)