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7 tháng 9 2020
a. \(\left(\frac{1}{3}x\right):\frac{2}{3}=1\frac{3}{4}:\frac{2}{5}\)
\(\left(\frac{1}{3}x\right):\frac{2}{3}=\frac{35}{8}\)
\(\frac{1}{3}x=\frac{35}{8}.\frac{2}{3}=\frac{35}{12}\)
\(x=\frac{35}{12}.3=\frac{35}{4}\)
b) 4,5:0,3=2,25:(0,1.x)
\(\frac{45}{10}:\frac{10}{3}=\frac{225}{100}:\left(\frac{1}{10}x\right)\)
\(15=\frac{9}{4}:\left(\frac{1}{10}x\right)\)
\(\frac{9}{4}:\left(\frac{1}{10}x\right)=15\)
\(\frac{1}{10}x=\frac{9}{4}.\frac{1}{15}=\frac{3}{20}\)
\(x=\frac{3}{20}.10=\frac{3}{2}\)
c) 8:\(\left(\frac{1}{4}x\right)=2:0,02\)
8:\(\left(\frac{1}{4}x\right)\)=2:\(\frac{2}{100}\)
8:\(\left(\frac{1}{4}x\right)=2.\frac{100}{2}=100\)
\(\frac{1}{4}x=\frac{8}{100}\)
\(x=\frac{8}{100}.4=\frac{8}{25}\)
d)\(3:2\frac{1}{4}=\frac{3}{4}:\left(6x\right)\)
\(3.\frac{9}{4}=\frac{3}{4}:\left(6x\right)\)
\(\frac{3}{4}:\left(6x\right)=\frac{27}{4}\)
\(6x=\frac{3}{4}.\frac{4}{27}=\frac{1}{9}\)
\(x=\frac{1}{9}.\frac{1}{6}=\frac{1}{54}\)
TK
30 tháng 9 2020
a, \(\frac{3}{5}+\frac{-1}{3}\)
=\(\frac{9}{15}+\frac{-5}{15}\)
=\(\frac{4}{15}\)
b,\(\frac{-2}{13}+\frac{-11}{26}\)
=\(\frac{-4}{26}+\frac{-11}{26}\)
=\(\frac{-15}{26}\)
c, \(-2+\frac{-5}{8}\)
=\(\frac{-16}{8}+\frac{-5}{8}\)
=\(\frac{-21}{8}\)
d,\(\frac{13}{30}-\frac{1}{5}\)
=\(\frac{13}{30}-\frac{6}{30}\)
=\(\frac{7}{30}\)
e,\(\frac{2}{21}-\frac{-1}{28}\)
=\(\frac{56}{588}-\frac{-21}{588}\)
=\(\frac{77}{588}=\frac{11}{84}\)
bài dễ mà <3
5 tháng 12 2018
\(\text{a,}\frac{2}{13}.\frac{-5}{3}+\frac{11}{13}.\frac{-5}{3}=-\frac{5}{3}\left(\frac{2}{13}+\frac{11}{13}\right)\)
\(=\frac{-5}{3}.\frac{13}{13}\)
\(=-\frac{5}{3}\)
\(\text{b,}\left(-\frac{1}{3}\right)^2+\left(-\frac{1}{3}\right)^3.27+\left(\frac{-2017}{2018}\right)^0=\frac{1}{9}-\frac{1}{27}.27+1\)
\(=\frac{1}{9}-1+1\)
\(=\frac{1}{9}\)
\(\text{c,}1,2-\sqrt{\frac{1}{4}}:1\frac{1}{20}+\left|\frac{3}{4}-1,25\right|-\left(\frac{-3}{2}\right)^2=\frac{6}{5}-\frac{1}{2}:\frac{21}{20}+\left|\frac{3}{4}-\frac{5}{4}\right|-\frac{9}{4}\)
\(=\frac{6}{5}-\frac{10}{21}+\frac{1}{2}-\frac{9}{4}\)
\(=\frac{-431}{420}\)
19 tháng 10 2016
mk làm bài 1 thui,bài 2 chỉ qui đồng ms
3a/6 = 3b/4 => 3(a-b)/ (6-4) = 3.4,5/2= 13,5/2 =k
a = 2k=13,5
b = 4k/3 =9
11 tháng 7 2018
a) \(\frac{3}{4}-\left|2x+1\right|=\frac{7}{8}\)
\(\left|2x+1\right|=\frac{3}{4}-\frac{7}{8}\)
\(\left|2x+1\right|=-\frac{1}{8}\)
\(\Rightarrow x\in\varnothing\)
b) \(2.\left|2x-3\right|=\frac{1}{2}\)
\(\left|2x-3\right|=\frac{1}{4}\)
TH1: 2x - 3 = 1/4
...
TH2: 2x -3 = -1/4
--
rùi bn tự lm típ nhé! câu c dựa vào phần a;b là lm đk
d)\(\left|x+\frac{4}{15}\right|-\left|-3,75\right|=-\left|-2,15\right|\)
\(\left|x+\frac{4}{15}\right|-3,75=-2,15\)
\(\left|x+\frac{4}{15}\right|=1,6\)
...
KV
29 tháng 10 2020
a) \(\left(\frac{2^2}{5}\right)+5\frac{1}{2}.\left(4,5-2,5\right)+\frac{2^3}{-4}\)
\(=\frac{4}{5}+\frac{11}{2}.2+\frac{-8}{4}\)
\(=\frac{4}{5}+11-2\)
\(=\frac{4}{5}+9\)
\(=\frac{49}{9}\)
b) \(\left(-2^3\right)+\frac{1}{2}:\frac{1}{8}-\sqrt{25}+\left|-64\right|\)
\(=-8+4-5+64\)
= 55
c) \(\frac{\sqrt{3^2+\sqrt{39}^2}}{\sqrt{91^2}-\sqrt{\left(-7\right)^2}}\)
\(=\frac{\sqrt{9+39}}{91-\sqrt{49}}\)
\(=\frac{\sqrt{48}}{91-7}\)
\(=\frac{4\sqrt{3}}{84}\)
\(=\frac{\sqrt{3}}{41}\)
d) Xem lại đề nhé em!
e) \(\sqrt{25}-3\sqrt{\frac{4}{9}}\)
\(=5-3.\frac{2}{3}\)
= 5 - 2
= 3
h) \(\left(-3^2\right).\frac{1}{3}-\sqrt{49}+\left(5^3\right):\sqrt{25}\)
\(=-9.\frac{1}{3}-7+125:5\)
\(=-3-7+25\)
= 15
\(\frac{3^2}{2}-\left(4,5-\frac{13}{2}\right)\)
\(=\frac92-\left(\frac92-\frac{13}{2}\right)\)
\(=\frac92-\frac92+\frac{13}{2}\)
\(=\frac{13}{2}\)
\(\frac{3}{2}^{2} = \frac{9}{4}\)
\(4 , 5 = \frac{9}{2}\)
suy ra
\(\frac{9}{4} - \left(\right. \frac{9}{2} - \frac{13}{2} \left.\right)\) \(= \frac{9}{4} - \frac{\left(\right. 9 - 13 \left.\right)}{2}\) \(= \frac{9}{4} - \frac{- 4}{2}\) \(= \frac{9}{4} + \frac{4}{2}\) \(= \frac{9}{4} + \frac{8}{4} = \frac{17}{4}\)
vậy
\(\frac{17}{4}\)