x = 2,075

\(\left|2\dfrac{1}{5}-x\right|\)\(+\left|x-\dfrac{1}{5}\right|\)\(+8\dfrac{1}{5}\)\(=1,2\)

\(\Rightarrow\left|2\dfrac{1}{5}-x\right|+\left|x-\dfrac{1}{5}\right|=\dfrac{6}{5}-\dfrac{41}{5}\)

\(\Rightarrow\left|2\dfrac{1}{5}-x\right|+\left|x-\dfrac{1}{5}\right|=\dfrac{-36}{5}\) (vô lý vì \(\left|2\dfrac{1}{5}-x\right|+\left|x-\dfrac{1}{5}\right|\ge0\))

Vậy: Không tìm được giá trị x thoả mãn.

\(1,2^3\cdot x^2=1,2^5\Leftrightarrow x^2=\dfrac{1,2^5}{1,2^3}=1,2^2=1,44\)

\(\Leftrightarrow x=1,2\) hoặc \(x=-1,2\)

Vậy x = 1,2 hoặc x = -1,2

(1,2)³.\(x^2\) = (1,2)⁵

         \(x^2\) = (1,2)⁵:(1,2)³

        \(x^2\) = (1,2)²

       \(\left[{}\begin{matrix}x=-1,2\\x=1,2\end{matrix}\right.\)

a) \(2^x=8\)

⇔ \(2^x=2^3\)

⇒ \(x=3\)

b) \(3^x=27\)

⇔ \(3^x=3^3\)

⇒ \(x=3\)

c) \(\left(-\dfrac{1}{2}\right)x=\left(-\dfrac{1}{2}\right)^4\)

⇔ \(x=\left(-\dfrac{1}{2}\right)^4\div\left(-\dfrac{1}{2}\right)\)

⇔ \(x=\left(-\dfrac{1}{2}\right)^3\)

d) \(x\div\left(-\dfrac{3}{4}\right)=\left(-\dfrac{3}{4}\right)^2\)

⇔ \(x=\left(-\dfrac{3}{4}\right)^2\cdot\left(-\dfrac{3}{4}\right)\)

⇔ \(x=\left(-\dfrac{3}{4}\right)^3=-\dfrac{27}{64}\)

d) \(\left(x+1\right)^3=-125\)

⇔ \(\left(x+1\right)^3=\left(-5\right)^3\)

⇔ \(x+1=-5\)

⇔ \(x=-5-1=-6\)

2:

a: (x-1,2)^2=4

=>x-1,2=2 hoặc x-1,2=-2

=>x=3,2(loại) hoặc x=-0,8(loại)

b: (x-1,5)^2=9

=>x-1,5=3 hoặc x-1,5=-3

=>x=-1,5(loại) hoặc x=4,5(loại)

c: (x-2)^3=64

=>(x-2)^3=4^3

=>x-2=4

=>x=6(nhận)

1,2 x 5,6 + 1,2 x 3,4 + 1,2

=6.72 + 4.08 + 1,2

=12

.

1,2*(5,6+3,4)+1,2

1,2*9+1,2

10,8+1,2

11

1,2 × 5,6 + 1,2 × 3,4 + 1,2

= 1,2 × ( 5,6 + 3,4 + 1 )

= 1,2 × 10

= 12

Học tốt nhé

Nhớ kết bạn với mk

a)

\(\begin{array}{l}{(1,2)^3}.x = {(1,2)^5}\\x = {(1,2)^5}:{(1,2)^3}\\x = {(1,2)^2}\\x = 1,44\end{array}\)

Vậy \(x = 1,44\).

b)

\(\begin{array}{l}{\left( {\frac{2}{3}} \right)^7}:x = {\left( {\frac{2}{3}} \right)^6}\\x = {\left( {\frac{2}{3}} \right)^7}:{\left( {\frac{2}{3}} \right)^6}\\x = \frac{2}{3}\end{array}\)

Vậy \(x = \frac{2}{3}\).

= 4 x 3 + 5 x 18 : 6 - 20 

= 12 + 5 x 18 : 6 - 20 

= 12 + 90 : 6 - 20 

= 102 : 6 - 20 

= 17 - 20 

= -3 

\(4,8:1,2\times3+5\times18:6-20\\ =4\times3+90:6-20\\ =12+15-20\\ =27-20\\ =7\)

 BÚ