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NH
0
NT
0
PN
9
2 tháng 5 2016
a) =-2,5+ -5,9+2/5
= (-2/5+2/5)+-5/9
= 0+-5/9
=-5/9
b) 17/13 - 4/13 + 11
= 1+11
= 12
c) 3/5 x (18/17+9/17 - 10/17)
= 3/5 x 1
= 3,5
TN
1 tháng 10 2018
\(120-\left\{17^{18}:17^{17}+2^2.\left[3.\left(21^{27}:21^{20}-5.3^3\right)\right]\right\}\)
\(=120-\left[17+4:\left(3.1801088406\right)\right]\)
\(=120-\left(17+4:5403265218\right)\)
\(=120-17\)
\(=103\)
học tốt
11 tháng 2 2018
\(\frac{-3}{7}+\left(\frac{2}{3}+\frac{3}{17}\right)=\frac{-3}{17}+\frac{2}{3}+\frac{3}{17}\)
\(=\left(\frac{-3}{17}+\frac{3}{17}\right)+\frac{2}{3}\)
\(=0+\frac{2}{3}=\frac{2}{3}\)
Q
25 tháng 3 2017
7) \(\dfrac{-5}{17}+\dfrac{3}{17}\le\dfrac{x}{17}\le\dfrac{13}{17}+\dfrac{-11}{17}\)
\(\Rightarrow\dfrac{-2}{17}\le\dfrac{x}{17}\le\dfrac{2}{17}\)
\(\Rightarrow-2\le x\le2\)
\(\Rightarrow x\in\left\{-2;-1;0;1;2\right\}\)
8) \(\dfrac{2}{3}\left(\dfrac{1}{2}+\dfrac{3}{4}-\dfrac{1}{3}\right)\le\dfrac{x}{18}\le\dfrac{7}{3}\left(\dfrac{1}{2}-\dfrac{1}{6}\right)\)
\(\Rightarrow\dfrac{2}{3}\left(\dfrac{6}{12}+\dfrac{9}{12}-\dfrac{4}{12}\right)\le\dfrac{x}{18}\le\dfrac{7}{3}\left(\dfrac{6}{12}-\dfrac{2}{12}\right)\)
\(\Rightarrow\dfrac{2}{3}\cdot\dfrac{11}{12}\le\dfrac{x}{18}\le\dfrac{7}{3}\cdot\dfrac{4}{12}\)
\(\Rightarrow\dfrac{22}{36}\le\dfrac{x}{18}\le\dfrac{28}{36}\)
\(\Rightarrow\dfrac{11}{18}\le\dfrac{x}{18}\le\dfrac{14}{18}\)
\(\Rightarrow x\in\left\{11;12;13;14\right\}\)
25 tháng 3 2017
8) \(\dfrac{2}{3}\left(\dfrac{1}{2}+\dfrac{3}{4}-\dfrac{1}{3}\right)\le\dfrac{x}{18}\le\dfrac{7}{3}\left(\dfrac{1}{2}-\dfrac{1}{6}\right)\\ \dfrac{2}{3}\left(\dfrac{6}{12}+\dfrac{9}{12}-\dfrac{4}{12}\right)\le\dfrac{x}{18}\le\dfrac{7}{3}\left(\dfrac{3}{6}-\dfrac{1}{6}\right)\\ \dfrac{2}{3}.\dfrac{11}{12}\le\dfrac{x}{18}\le\dfrac{7}{3}.\dfrac{2}{6}\\ \dfrac{11}{18}\le\dfrac{x}{18}\le\dfrac{14}{18}\\ \Rightarrow11\le x\le14\\ \Rightarrow x\in\left\{11;12;13;14\right\}\)
-3/17+43/51 =2/3
\(-\dfrac{3}{17}+\left(\dfrac{2}{3}+\dfrac{3}{17}\right)=-\dfrac{3}{17}+\dfrac{3}{17}+\dfrac{2}{3}=\dfrac{2}{3}\)