ai alfm vote 5 sao cho ctlhn

Đáp án+Giải thích các bước giải:

`a) x : (9(1)/(2) - 3/2) =` $\dfrac{0,4+\dfrac{2}{9}-\dfrac{2}{11}}{1,6+\dfrac{8}{9}-\dfrac{8}{11}}$ 

`⇔` `x : (19/2 - 3/2) = ` $\dfrac{2(0,2+\dfrac{1}{9}-\dfrac{1}{11})}{8(0,2+\dfrac{1}{9}-\dfrac{1}{11})}$ 

`⇔` `x : 8 = 2/8`

`⇔ x = 2/8 . 8`

`⇔ x = 2`

Vậy `x = 2`

`b) (x+1)/2 = 8/(x+1)`

`⇔ (x+1)(x+1) = 8.2`

`⇔ (x+1)^2 = 16`

`⇔ (x+1)^2 = (±4)^2`

`⇔` \(\left[ \begin{array}{l}x+1=4\\x+1=-4\end{array} \right.\) 

`⇔` \(\left[ \begin{array}{l}x=4-1\\x=-4-1\end{array} \right.\) 

`⇔` \(\left[ \begin{array}{l}x=3\\x=-5\end{array} \right.\) 

Mà `x in N`

`⇔ x = 3`

Vậy `x = 3`

`e) 5^(2x-3) - 2.5^2 = 5^2 . 3`

`⇔ 5^(2x-3) - 2.25 = 25.3`

`⇔ 5^(2x-3) - 50 = 75`

`⇔ 5^(2x-3) = 75 + 50`

`⇔ 5^(2x-3) = 125`

`⇔ 5^(2x-3) = 5^3`

`⇔ 2x - 3 = 3`

`⇔ 2x = 3+3`

`⇔ 2x = 6`

`⇔ x = 6:2`

`⇔ x = 3`

Vậy `x = 3`

`d) |2x-7| = 20 + 5.(-3)`

`⇔ |2x-7| = 20 + (-15)`

`⇔ |2x - 7| = 5`

`⇔` \(\left[ \begin{array}{l}2x-7=5\\2x-7=-5\end{array} \right.\) 

`⇔` \(\left[ \begin{array}{l}2x=5+7\\2x=(-5)+7\end{array} \right.\) 

`⇔` \(\left[ \begin{array}{l}2x=12\\2x=-2\end{array} \right.\) 

`⇔` \(\left[ \begin{array}{l}x=12:2\\x=-2:2\end{array} \right.\) 

`⇔` \(\left[ \begin{array}{l}x=6\\x=-1\end{array} \right.\) 

Mà `x in N`

`⇔` `x = 6`

Vậy `x = 6`