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14 tháng 7 2017

binh rồi căn thì cứ chuyển bỏ dấu âm đi nó tương tự dấu giá trị tuyệt đối thôi

a) \(\frac{-6}{21}.\frac{3}{2}=-\frac{3}{7}\)          b) \(\left(-3\right).\left(\frac{-7}{12}\right)=\frac{21}{12}=\frac{7}{4}\)

c) \(\left(\frac{11}{12}:\frac{33}{16}\right).\frac{3}{5}=\frac{11}{12}.\frac{16}{33}.\frac{3}{5}=\frac{4}{15}\)

d) \(\sqrt{\left(-7\right)^2}+\sqrt{\frac{2}{16}}=7+\sqrt{\frac{1}{8}}\)

c) \(\frac{1}{2}.\sqrt{100}-\sqrt{\frac{1}{16}}+\left(\frac{1}{3}\right)^0=\frac{1}{2}.10-\frac{1}{4}+1=5\frac{3}{4}\)

27 tháng 6 2019

\(a,\frac{1}{2}+\frac{2}{3}x=\frac{4}{5}\)

=> \(\frac{2}{3}x=\frac{4}{5}-\frac{1}{2}=\frac{3}{10}\)

=> \(x=\frac{3}{10}:\frac{2}{3}=\frac{9}{20}\)

Vậy \(x\in\left\{\frac{9}{20}\right\}\)

\(b,x+\frac{1}{4}=\frac{4}{3}\)

=> \(x=\frac{4}{3}-\frac{1}{4}=\frac{13}{12}\)

Vậy \(x\in\left\{\frac{13}{12}\right\}\)

\(c,\frac{3}{5}x-\frac{1}{2}=-\frac{1}{7}\)

=> \(\frac{3}{5}x=-\frac{1}{7}+\frac{1}{2}=\frac{5}{14}\)

=> \(x=\frac{5}{14}:\frac{3}{5}=\frac{25}{42}\)

Vậy \(x\in\left\{\frac{25}{42}\right\}\)

\(d,\left|x+5\right|-6=9\)

=> \(\left|x+5\right|=9+6=15\)

=> \(\left[{}\begin{matrix}x+5=15\\x+5=-15\end{matrix}\right.\)

=> \(\left[{}\begin{matrix}x=15-5=10\\x=-15-5=-20\end{matrix}\right.\)

Vậy \(x\in\left\{10;-20\right\}\)

\(e,\left|x-\frac{4}{5}\right|=\frac{3}{4}\)

=> \(\left[{}\begin{matrix}x-\frac{4}{5}=\frac{3}{4}\\x-\frac{4}{5}=-\frac{3}{4}\end{matrix}\right.\)

=> \(\left[{}\begin{matrix}x=\frac{3}{4}+\frac{4}{5}=\frac{31}{20}\\x=-\frac{3}{4}+\frac{4}{5}=\frac{1}{20}\end{matrix}\right.\)

Vậy \(x\in\left\{\frac{31}{20};\frac{1}{20}\right\}\)

\(f,\frac{1}{2}-\left|x\right|=\frac{1}{3}\)

=> \(\left|x\right|=\frac{1}{2}-\frac{1}{3}\)

=> \(\left|x\right|=\frac{1}{6}\)

=> \(\left[{}\begin{matrix}x=\frac{1}{6}\\x=-\frac{1}{6}\end{matrix}\right.\)

Vậy \(x\in\left\{\frac{1}{6};-\frac{1}{6}\right\}\)

\(g,x^2=16\)

=> \(\left|x\right|=\sqrt{16}=4\)

=> \(\left[{}\begin{matrix}x=4\\x=-4\end{matrix}\right.\)

vậy \(x\in\left\{4;-4\right\}\)

\(h,\left(x-\frac{1}{2}\right)^3=\frac{1}{27}\)

=> \(x-\frac{1}{2}=\sqrt[3]{\frac{1}{27}}=\frac{1}{3}\)

=> \(x=\frac{1}{3}+\frac{1}{2}=\frac{5}{6}\)

Vậy \(x\in\left\{\frac{5}{6}\right\}\)

\(i,3^3.x=3^6\)

\(x=3^6:3^3=3^3=27\)

Vậy \(x\in\left\{27\right\}\)

\(J,\frac{1,35}{0,2}=\frac{1,25}{x}\)

=> \(x=\frac{1,25.0,2}{1,35}=\frac{5}{27}\)

Vậy \(x\in\left\{\frac{5}{27}\right\}\)

\(k,1\frac{2}{3}:x=6:0,3\)

=> \(\frac{5}{3}:x=20\)

=> \(x=\frac{5}{3}:20=\frac{1}{12}\)

Vậy \(x\in\left\{\frac{1}{12}\right\}\)

27 tháng 2 2019

\(\left[\left(4.4+1\right)\sqrt{\frac{3}{2}.2}\right].x=\sqrt{6400}+\sqrt{6400}.2\)

\(\Rightarrow\left[17.\sqrt{3}\right].x=80+80.2\)

\(\Rightarrow17\sqrt{3}.x=240\)

\(\Rightarrow x=\frac{240}{17\sqrt{3}}\)

20 tháng 8 2020

a. \(\left(2-\frac{3}{4}\right)^2:\frac{11}{16}=\frac{5}{4}^2.\frac{11}{16}=\frac{25}{16}.\frac{16}{11}=\frac{25}{11}\)

b. \(2^3.\frac{7}{20}+\frac{7}{10}=8.\frac{7}{20}+\frac{7}{10}=\frac{14}{5}+\frac{7}{10}=\frac{7}{2}\)

c. \(\sqrt{3^2+4^2}-\sqrt{1^3+2^3+3^3}=\sqrt{9+16}-\sqrt{1+8+27}\)

\(=\sqrt{25}-\sqrt{36}=5-6=-1\)

d. \(21^3:\left(-7\right)^3=\left(21:\left(-7\right)\right)^3=-3^3=-27\)

a) \(\left(2-\frac{3}{4}\right)^2\div\frac{11}{16}=\left(\frac{5}{4}\right)^2.\frac{16}{11}=\frac{25}{16}.\frac{16}{11}=\frac{25}{11}\)

b) \(2^3.\frac{7}{20}+\frac{7}{10}=8.\frac{7}{20}+\frac{7}{10}=\frac{14}{5}+\frac{7}{10}=\frac{7}{2}\)

c) \(\sqrt{3^2+4^2}-\sqrt{1^3+2^3+3^3}=\sqrt{9+16}-\sqrt{1+8+27}\)

\(=\sqrt{25}-\sqrt{36}=5-6=-1\)

d) \(\frac{21^3}{\left(-7\right)^3}=\frac{9261}{-343}=-27\)