`x+5/9=18/27`

`x+5/9=2/3`

`x=2/3-5/9`

`x=6/9-5/9`

`x=1/9`

______________________________________

`x:1/2-5/4=4/7`

`x:1/2=4/7+5/4`

`x:1/2=16/28 + 35/28`

`x:1/2=51/28`

`x=51/28 xx 1/2`

`x=51/56`

`(x-1/3) . 1 2/3 = 14/27 - 3/9`

`(x-1/3). 1 2/3 = 14/27 - 9/27`

`(x-1/3). 1 2/3 = 5/27`

`(x-1/3) . 5/3 = 5/27`

`x-1/3 = 5/27 : 5/3`

`x-1/3 = 5/27 . 3/5`

`x-1/3 = 1/9`

`x=1/9+1/3`

`x=1/9+3/9`

`x=4/9`

Vậy `x=4/9`

`9/5 xx 15/17 + 8/5 xx 15/17`

`=15/17 xx (9/5+8/5)`

`=15/17 xx ((8+9)/5)`

`=15/17 xx 17/5`

`=(15xx17)/(17xx5)`

`=15/5`

`=3`

9/5 . 15.17 + 8/5 . 15/17 

=( 9/5 + 8/5 ) . 15/17

= 17/5 .15/17

 = 3

Mẫu số chung: `180`

`3/9=1/3 =(3xx20)/(9xx20)=60/180`

`4/5=(4xx36)/(5xx36)=144/180`

`7/4=(7xx45)/(4xx45)=315/180`

\(=\dfrac{18}{11}\left(\dfrac{35-12}{20}\right):\dfrac{1}{2}=\dfrac{18}{11}.\dfrac{23}{20}:\dfrac{1}{2}=\dfrac{18}{11}.\dfrac{46}{20}=\dfrac{207}{55}\)

`18/11 . (7/4 - 3/5):1/2`

`=18/11 . (35/20 - 12/20):1/2`

`=18/11 . 23/20 : 1/2`

`=18/11 . 23/20 . 2`

`=(18.23.2)/(11.20)`

`=207/55`

\(3x^2+5x+5=3x^2+25\Leftrightarrow5x=20\Leftrightarrow x=4\)

\(x^2+8x+1=x^2+75\Leftrightarrow8x=74\Leftrightarrow x=\dfrac{37}{4}\)

3⁵.3^x=9.3⁵

⇒ 3^5+x=3².3⁵

⇒ 3^5+x=3⁷

⇒   5+x=7

⇒       x=7-5

⇒       x=2

35.3x=9.35

⇒ 35+x=32.35

⇒ 35+x=37

⇒   5+x=7

⇒       x=7-5

⇒       x=2

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