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11 tháng 7 2016

16+3(x-7)=43

3(x-7)=43-16

a,3(x-7)=27

x-7=27:3

x-7=9

x=9+7

x=16

b,28-2(x+5)=14

  2(x+5)=28-14

 2(x+5)=14

x+5=14:2

x+5=7

x=7-5

x=2

11 tháng 7 2016

                              

a) <-->\(3\left(x-7\right)=43-16\)

    <--> \(3x-21=27\)

    <--> \(3x=27+21\)

    <--> \(3x=48\)

    <--> \(x=16\)

b) <--> \(-2\left(x+5\right)=14-28\)

    <-->  \(-2\left(x+5\right)=-14\)

    <-->   \(-2x-10=-14\)

    <-->    \(-2x=-14+10\)

     <-->    \(-2x=-4\)

     <-->     \(x=2\)

29 tháng 12 2022

a.\(\left(-12\right)x-14=-2\)

\(\left(-12\right)x=-2+14\)

\(\left(-12\right)x=12\)

\(x=12:\left(-12\right)\)

\(x=-1\)

 

\(b,\left(-8\right)x=\left(-5\right)\left(-7\right)-3\)

\(\left(-8\right)x=35-3\)

\(\left(-8\right)x=32\)

\(x=32:\left(-8\right)\)

\(x=-4\)

 

\(c,\left(-9\right)x+3=\left(-2\right)\left(-7\right)+16\)

\(\left(-9\right)x+3=14+16\)

\(\left(-9\right)x+3=30\)

\(\left(-9\right)x=30-3\)

\(\left(-9\right)x=27\)

\(x=27:\left(-9\right)\)

\(x=-3\)

Bài 1: 

1: =-5/24+16/27+3/4

=-5/24+18/24+16/27

=13/24+16/27

=117/216+128/216=245/216

2: =-1/3+1/3+6/7=6/7

3: \(=\dfrac{1}{2}-\dfrac{7}{12}+\dfrac{1}{2}=1-\dfrac{7}{12}=\dfrac{5}{12}\)

4: \(=-\dfrac{5}{8}+\dfrac{14}{25}-\dfrac{6}{10}=\dfrac{-125+112-120}{200}=\dfrac{-133}{200}\)

2 tháng 8 2016

tìm x hả bạn

2 tháng 8 2016

      200-2(x+6)=14

=> 2(x+6)=200-14

=> 2(x+6)=186

 => x+6=186:2

=> x+6=93

=> x=93-6

=> x=87

            

a) Ta có: \(\dfrac{2}{3}x-1=\dfrac{3}{2}\)

\(\Leftrightarrow x\cdot\dfrac{2}{3}=\dfrac{5}{2}\)

hay \(x=\dfrac{5}{2}:\dfrac{2}{3}=\dfrac{5}{2}\cdot\dfrac{3}{2}=\dfrac{15}{4}\)

b) Ta có: \(\left|5x-\dfrac{1}{2}\right|-\dfrac{2}{7}=25\%\)

\(\Leftrightarrow\left|5x-\dfrac{1}{2}\right|=\dfrac{1}{4}+\dfrac{2}{7}=\dfrac{15}{28}\)

\(\Leftrightarrow\left[{}\begin{matrix}5x-\dfrac{1}{2}=\dfrac{15}{28}\\5x-\dfrac{1}{2}=\dfrac{-15}{28}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}5x=\dfrac{29}{28}\\5x=\dfrac{-1}{28}\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{29}{140}\\x=\dfrac{-1}{140}\end{matrix}\right.\)

c) Ta có: \(\dfrac{x-3}{4}=\dfrac{16}{x-3}\)

\(\Leftrightarrow\left(x-3\right)^2=64\)

\(\Leftrightarrow\left[{}\begin{matrix}x-3=8\\x-3=-8\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=11\\x=-5\end{matrix}\right.\)

d) Ta có: \(\dfrac{-8}{13}+\dfrac{7}{17}+\dfrac{21}{31}\le x\le\dfrac{-9}{14}+4-\dfrac{5}{14}\)

\(\Leftrightarrow\dfrac{3246}{6851}\le x\le3\)

\(\Leftrightarrow x\in\left\{1;2;3\right\}\)

a)\(3^9:3^7+5\times2^3\)

\(9+40=49\)

b)\(2^3\times3^2-5^{16}:5^{14}\)

\(72-25=47\)

11 tháng 7 2017

a)   \(3^9:3^7+5\text{×}2^3=3^2+5\text{×}8=9+40=49\)

b)   \(2^3\text{×}3^2-5^{16}:5^{14}=8\text{×}9-5^2=72-25=47\)