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5^x + 5^ ( x + 2 ) = 650
5x + 5x . 52 = 650
5x .( 1 + 25 ) = 650
5x . 26 = 650
5x = 650 : 26
5x = 25
5x = 52
=> x = 2
Vậy x = 2

`@` `\text {Ans}`
`\downarrow`
`3)`
`(2x + 1) \div 9 - 104 \div 13 = 27^2 \div 3^5`
`\Rightarrow (2x + 1) \div 9 - 8 = (3^3)^2 \div 3^5`
`\Rightarrow (2x + 1) \div 9 - 8 = 3^6 \div 3^5`
`\Rightarrow (2x + 1) \div 9 - 8 = 3`
`\Rightarrow (2x + 1) \div 9 = 3 + 8`
`\Rightarrow (2x + 1) \div 9 = 11`
`\Rightarrow 2x + 1 = 11 . 9`
`\Rightarrow 2x + 1 = 99`
`\Rightarrow 2x = 99 - 1`
`\Rightarrow 2x = 98`
`\Rightarrow x = 98 \div 2`
`\Rightarrow x = 49`
Vậy, `x = 49.`
3) \(\left(2x+1\right):9-104:13=27^2:3^5\)
\(\left(2x+1\right):9-8=729:243\)
\(\left(2x+1\right):9-8=3\)
\(\left(2x+1\right):9=8+3\)
\(\left(2x+1\right):9=11\)
( 2x + 1) = 11.9
2x+1 = 99
2x = 99-1
2x = 98
x = 98 : 2
x = 49


a) \(\frac{5}{13}+2x=\frac{3}{13}\)
\(2x=\frac{3}{13}-\frac{5}{13}=\frac{-2}{13}\)
\(x=\frac{-2}{13}:2=\frac{-2}{13}.\frac{1}{2}=\frac{-1}{13}\)
b) 20% x - 0,7x = 15%
(20% - 0,7)x = 15%
-1/2 x = 15%
x = 15% : (-1/2)
x = -3/10

a: \(=\dfrac{-3}{5}\cdot\dfrac{5}{7}+\dfrac{-3}{5}\cdot\dfrac{3}{7}+\dfrac{-3}{5}\cdot\dfrac{6}{7}\)
\(=\dfrac{-3}{5}\left(\dfrac{5}{7}+\dfrac{3}{7}+\dfrac{6}{7}\right)=\dfrac{-3}{5}\cdot2=-\dfrac{6}{5}\)
b: \(=\dfrac{3}{13}\cdot\dfrac{6}{11}+\dfrac{3}{13}\cdot\dfrac{5}{11}-\dfrac{2}{13}=\dfrac{3}{13}-\dfrac{2}{13}=\dfrac{1}{13}\)
c: =>1/2x+1+3/8=7/16
=>1/2x=-15/16
=>x=-15/8
d: =>5/2x-1/3=1/6*(-9)/2=-9/12=-3/4
=>5/2x=-3/4+1/3=-9/12+4/12=-5/12
=>x=-1/6

a) \(x-2=-6\)
\(x=-6+2\)
\(x=-4\)
2) \(-5x-\left(-3\right)=13\)
\(-5x+3=13\)
\(-5x=13-3\)
\(-5x=10\)
\(x=-2\)
3) \(15-\left(x-7\right)=-21\)
\(15-x+7=-21\)
\(22-x=-21\)
\(x=22+21\)
\(x=43\)
b) \(2x-\left(-17\right)=15\)
\(2x+17=15\)
\(2x=15-17\)
\(2x=-2\)
\(x=-1\)
5) \(\left|x-3\right|-7=13\)
\(\left|x-3\right|=20\)
\(\Rightarrow\orbr{\begin{cases}x-3=20\\x-3=-20\end{cases}}\Rightarrow\orbr{\begin{cases}x=23\\x=-17\end{cases}}\)

\(\frac{2x}{4}:-5=\frac{1}{7}\)
\(\frac{x}{2}=-\frac{5}{7}\)
\(x=-\frac{10}{7}\)