Question

Bài 2:

a)|x - 2/3|- 5/4= 0

b)1,35 /0,2 = 1,25 /0,1x

c)3cân bậc x - 5cân bậc x =-6

d)3^x+2.2^x-1=36³

^{giúp mình với!}

Answer 1

\(a,\Rightarrow\left[{}\begin{matrix}x-\dfrac{2}{3}=\dfrac{5}{4}\\\dfrac{2}{3}-x=\dfrac{5}{4}\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=\dfrac{23}{12}\\x=-\dfrac{7}{12}\end{matrix}\right.\\ b,\Rightarrow0,1x\cdot1,35=0,2\cdot1,25=0,25\\ \Rightarrow0,135x=0,25\Rightarrow x=\dfrac{50}{27}\\ c,ĐK:x\ge0\\ PT\Leftrightarrow-2\sqrt{x}=-6\Leftrightarrow x=9\left(tm\right)\\ d,\Leftrightarrow3^{x+2}\cdot2^{x-1}=\left(3^2\cdot2^2\right)^3=3^6\cdot2^6\\ \Leftrightarrow\left\{{}\begin{matrix}x+2=6\\x-1=6\end{matrix}\right.\Leftrightarrow x\in\varnothing\)

Answer 2

a) I\(x - \dfrac{2}{3} \)I \(- \dfrac{5}{4} = 0\)

    I\(x - \dfrac{2}{3} \)I = 0 +\(\dfrac{5}{4} \)

    I\(x - \dfrac{2}{3} \)I = \(\dfrac{5}{4} \)

    I\(x - \dfrac{2}{3} \)I = \(\begin{cases} \dfrac{5}{4} + \dfrac{2}{3}\\ \dfrac{-5}{4} + \dfrac{2}{3}\\ \end{cases} \)

    \(x \) = \(\begin{cases} \dfrac{23}{12} \\ \dfrac{-7}{12} \end{cases} \)

   

Answer 3

b) \(\dfrac{1,35}{0,2} = \dfrac{1,25}{0,1x}\)

     1,35 . 0,1x = 1,25 . 0,2

     1,35 . 0,1x = 0,25

      0,1x = 0,25 : 1,35 

      \(\dfrac{1}{10}\)x = \(\dfrac{5}{27}\)

       x = \(\dfrac{5}{27} : \dfrac{1}{10}\)

       x = \(\dfrac{5}{27} . \dfrac{10}{1}\)

       x = \(\dfrac{50}{27}\)

Answer 4

3\(\sqrt{x - 5}\) , \(\sqrt{x} = -6\)

\(\sqrt{x} = - 6 => x = 36\)

Thay x vào 3\(\sqrt{x - 5}\) ta có:

3\(\sqrt{x - 5}\) = 3\(\sqrt{36 - 5}\) = 3\(\sqrt{31}\)≈ 16,7

Answer 5

3^{x + 2} . 2^{x - 1} = 36³

3^{x + 2} . 2^{x - 1} = 6⁶

3^{x + 2} . 2^{x - 1} = 3⁶ . 2⁶

=> x + 2 = 6 => x = 4

=> x - 1 = 6 => x = 7