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Câu 1:
a)\(\frac{3}{4}-0,25-\left[\frac{7}{3}+\left(-\frac{9}{2}\right)\right]-\frac{5}{6}\)
\(=\frac{3}{4}-\frac{1}{4}-\frac{14}{6}+\frac{27}{6}-\frac{5}{6}\)
\(=\frac{1}{2}-\frac{4}{3}\)
\(=-\frac{5}{6}\)
b)\(7+\left(\frac{7}{12}-\frac{1}{2}+3\right)-\left(\frac{1}{12}+5\right)\)
\(=7+\frac{1}{12}+3-\frac{1}{12}-5\)
\(=5\)
Câu 2:
\(\frac{3}{4}-\frac{5}{6}\le\frac{x}{12}< 1-\left(\frac{2}{3}-\frac{1}{4}\right)\)
\(-\frac{1}{12}\le\frac{x}{12}< 1-\frac{5}{12}\)
\(-\frac{1}{12}\le\frac{x}{12}< \frac{7}{12}\)
Vậy -1\(\le\)x<7
Bài 1:
a) \(\frac{1}{5}x^4y^3-3x^4y^3\)
= \(\left(\frac{1}{5}-3\right)x^4y^3\)
= \(-\frac{14}{5}x^4y^3.\)
b) \(5x^2y^5-\frac{1}{4}x^2y^5\)
= \(\left(5-\frac{1}{4}\right)x^2y^5\)
= \(\frac{19}{4}x^2y^5.\)
Mình chỉ làm 2 câu thôi nhé, bạn đăng nhiều quá.
Chúc bạn học tốt!
Ta có: A = \(\left|\frac{4}{9}-\left(\frac{\sqrt{2}}{2}\right)^2\right|+\left|0,\left(4\right)+\frac{\frac{1}{3}-\frac{2}{5}-\frac{3}{7}}{\frac{2}{3}-\frac{4}{5}-\frac{6}{7}}\right|\)
= \(\left|\frac{4}{7}-\frac{\sqrt{2}^2}{2^2}\right|+\left|0,\left(1\right).4+\frac{\frac{1}{3}-\frac{2}{5}-\frac{3}{7}}{2\left(\frac{1}{3}-\frac{2}{5}-\frac{3}{7}\right)}\right|\)
= \(\left|\frac{4}{7}-\frac{1}{2}\right|+\left|\frac{1}{9}.4+\frac{1}{2}\right|\)
= \(\left|\frac{8-7}{14}\right|+\left|\frac{8+9}{18}\right|\)
= \(\left|\frac{1}{14}\right|+\left|\frac{17}{18}\right|\)
= 1/14 + 17/18 = 64/63
A = \(\left|\frac{4}{9}-\left(\frac{\sqrt{2}}{2}\right)^2\right|+\left|0,\left(4\right)+\frac{\frac{1}{3}-\frac{2}{5}-\frac{3}{7}}{\frac{2}{3}-\frac{4}{5}-\frac{6}{7}}\right|\)
= \(\left|\frac{4}{9}-\left(\frac{\sqrt{2}^2}{2^2}\right)\right|+\left|0,\left(1\right).4+\frac{\frac{1}{3}-\frac{2}{5}-\frac{3}{7}}{2.\left(\frac{1}{3}-\frac{2}{5}-\frac{3}{7}\right)}\right|\)
= \(\left|\frac{4}{9}-\frac{1}{2}\right|+\left|\frac{1}{9}.4+\frac{1}{2}\right|\)
= \(\left|\frac{8-9}{18}\right|+\left|\frac{4}{9}+\frac{1}{2}\right|\)
= \(\left|-\frac{1}{18}\right|+\left|\frac{8+9}{18}\right|\)
= \(\frac{1}{18}+\frac{17}{18}=1\)
\(=\frac{16}{5}.\frac{15}{16}-\left(\frac{3}{4}+\frac{2}{7}\right):\left(\frac{-29}{28}\right)\)
\(=3-\left(\frac{21}{28}+\frac{8}{28}\right):\left(\frac{-29}{28}\right)\)
\(=3-\left(\frac{29}{28}\right).\left(\frac{-28}{29}\right)\)
\(=3-\left(-1\right)\)
\(=4\)
b) \(=\left(\frac{1}{4}+\frac{25}{2}-\frac{5}{16}\right):\left(12-\frac{7}{12}:\left(\frac{3}{8}-\frac{1}{12}\right)\right)\)
\(=\left(\frac{4}{16}+\frac{200}{16}-\frac{5}{16}\right):\left(12-\frac{7}{12}:\left(\frac{3.3}{2.3.4}-\frac{2}{2.3.4}\right)\right)\)
\(=\left(\frac{199}{16}\right):\left(12-\frac{7}{12}:\left(\frac{9}{24}-\frac{2}{24}\right)\right)\)
\(=\frac{199}{16}:\left(12-\frac{7}{12}.\frac{24}{7}\right)\)
\(=\frac{199}{16}:\left(12-2\right)\)
\(=\frac{199}{16}:10\)
\(=\frac{199}{160}\)
c) \(\left(\frac{-3}{5}+\frac{5}{11}\right):\frac{-3}{7}+\left(\frac{-2}{5}+\frac{6}{5}\right):\frac{-3}{7}\)
\(\left(\frac{-33}{55}+\frac{25}{55}\right):\frac{-3}{7}+\left(\frac{4}{5}\right):\frac{-3}{7}\)
\(\left(\frac{-8}{55}\right).\frac{-7}{3}+\frac{4}{5}.\frac{-7}{3}\)
\(\frac{-7}{3}\left(\frac{-8}{55}+\frac{4}{5}\right)\)
\(\frac{-7}{3}.\frac{36}{55}=\frac{-84}{55}\)
\(\frac{x}{12}=\frac{y}{3}=\frac{x}{12}=\frac{2y}{6}\)
Áp dụng tính chất dãy tỉ số bằng nhau:
\(\frac{x}{12}=\frac{2y}{6}\Rightarrow\frac{x-2y}{12-6}=\frac{36}{6}=6\)
\(\frac{x}{12}=6\Rightarrow x=6.12=72\)
\(\frac{2y}{6}=6\Rightarrow2y=6.6\Rightarrow2y=36\Rightarrow y=36:2=18\)
Vậy...
a) \(\frac{x}{12}=\frac{y}{3}\)và \(x-2y=36\)
Áp dụng tính chất của dãy tỉ số bằng nhau :
Ta có : \(\frac{x}{12}=\frac{2y}{3}=\frac{x-2y}{12-3}=\frac{x-2y}{12-6}=\frac{36}{6}=6\)
\(\frac{x}{12}=6\Rightarrow x=72\)
\(\frac{2y}{6}=6\Rightarrow2y=36\Rightarrow y=18\)
Vậy ...