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\(\frac{-6}{-35}:\frac{27}{180}+-\frac{3}{28}=\frac{6}{35}.\frac{180}{27}+-\frac{3}{28}=\frac{8}{7}+-\frac{3}{28}=\frac{32}{28}+-\frac{3}{28}=\frac{29}{28}\)
\(\frac{-6}{-35}:\frac{27}{180}+\frac{-3}{28}\)
\(=\frac{6}{35}\cdot\frac{180}{27}-\frac{3}{28}\)
\(=\frac{2\cdot3}{5\cdot7}\cdot\frac{5\cdot4\cdot9}{3\cdot9}-\frac{3}{28}\)
\(=\frac{8}{7}-\frac{3}{28}\)
\(=\frac{32}{28}-\frac{3}{28}\)
\(=\frac{29}{28}\)
`#3107.101107`
\(2^2\cdot5^2-18\div3^2\\ =\left(2\cdot5\right)^2-18\div9\\ =10^2-9\\ =100-9\\ =91\)
Quy ước toán học dấu x = dấu .
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1. (3x - 5)4 = 28
<=> (3x - 5)4 = 44
=> Ta có 2 trường hợp :
* TH1 : \(3^x-5=4\Rightarrow3^x=9\Rightarrow x=2\)
* TH2 : \(3^x-5=-4\Rightarrow3^x=1\Rightarrow x=0\)
Vậy x=1 hoặc x=0
\(3+3^2+.....+3^{99}\)
\(=\left(3+3^2+3^3\right)+\left(3^4+3^5+3^6\right)+...+\left(3^{97}+3^{98}+3^{99}\right)\)
\(=39+3^3\left(3+3^2+3^3\right)+........+3^{96}\left(3+3^2+3^3\right)\)
\(=39+3^3\cdot39+...+3^{96}\cdot39\)
\(=39\left(1+3^3+....+3^{96}\right)\)
Vì \(39⋮13\Rightarrow39\in B\left(13\right)\)
`@` `\text {Ans}`
`\downarrow`
`1)`
\(2x+\dfrac{1}{2}=\dfrac{5}{3}\)
`\Rightarrow`\(2x=\dfrac{5}{3}-\dfrac{1}{2}\)
`\Rightarrow`\(2x=\dfrac{7}{6}\)
`\Rightarrow`\(x=\dfrac{7}{6}\div2\)
`\Rightarrow`\(x=\dfrac{7}{12}\)
Vậy, `x = 7/12`
`2)`
\(\dfrac{1}{7}+\dfrac{4}{5}x=\dfrac{5}{3}\)
`\Rightarrow`\(\dfrac{4}{5}x=\dfrac{5}{3}-\dfrac{1}{7}\)
`\Rightarrow`\(\dfrac{4}{5}x=\dfrac{32}{21}\)
`\Rightarrow`\(x=\dfrac{32}{21}\div\dfrac{4}{5}\)
`\Rightarrow`\(x=\dfrac{40}{21}\)
Vậy, `x = 40/21`
`3)`
\(\dfrac{3}{5}-\dfrac{3}{5}x=\dfrac{1}{7}\)
`\Rightarrow`\(\dfrac{3}{5}x=\dfrac{3}{5}-\dfrac{1}{7}\)
`\Rightarrow`\(\dfrac{3}{5}x=\dfrac{16}{35}\)
`\Rightarrow`\(x=\dfrac{16}{35}\div\dfrac{3}{5}\)
`\Rightarrow`\(x=\dfrac{16}{21}\)
Vậy, `x = 16/21`
`4)`
\(\dfrac{5}{6}-3x=\dfrac{3}{4}\)
`\Rightarrow`\(3x=\dfrac{5}{6}-\dfrac{3}{4}\)
`\Rightarrow`\(3x=\dfrac{1}{12}\)
`\Rightarrow`\(x=\dfrac{1}{12}\div3\)
`\Rightarrow`\(x=\dfrac{1}{36}\)
Vậy, `x = 1/36`
`5)`
\(\dfrac{5}{3}-\dfrac{1}{2}x=\dfrac{3}{7}\)
`\Rightarrow`\(\dfrac{1}{2}x=\dfrac{5}{3}-\dfrac{3}{7}\)
`\Rightarrow`\(\dfrac{1}{2}x=\dfrac{26}{21}\)
`\Rightarrow`\(x=\dfrac{26}{21}\div\dfrac{1}{2}\)
`\Rightarrow`\(x=\dfrac{52}{21}\)
Vậy, `x = 52/21`
`6)`
\(5x+\dfrac{1}{2}=\dfrac{2}{3}\)
`\Rightarrow`\(5x=\dfrac{2}{3}-\dfrac{1}{2}\)
`\Rightarrow`\(5x=\dfrac{1}{6}\)
`\Rightarrow`\(x=\dfrac{1}{6}\div5\)
`\Rightarrow`\(x=\dfrac{1}{30}\)
Vậy, `x = 1/30.`
Đề: Tính
32 . 23 + 33 . 27 = 32 . 8 + 32 . 81
= 32 (8 + 81)
= 9 . 89 = 801
Tính như bình thường thôi , kết quả là 801.