dễ mà bạn

a) x=4/7 - 1/3=19/21

b) /x-5/=7 -->x-5=7 hoặc x-5=-7

--> x=12 hoặc x= -2

a,\(\frac{4}{7}-x=\frac{1}{3}\Rightarrow x=\frac{4}{7}-\frac{1}{3}\)

\(\Rightarrow x=\frac{12}{21}-\frac{7}{21}\Rightarrow x=\frac{5}{21}\)

b,\(\left|x-5\right|=7\Rightarrow\orbr{\begin{cases}x-5=7\\x-5=-7\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=12\\x=-2\end{cases}}\)

c,\(x-\frac{2}{3}=-\frac{6}{7}\Rightarrow x=-\frac{6}{7}+\frac{2}{3}\Rightarrow x=-\frac{4}{21}\)

d,\(\frac{x}{3}=\frac{8}{12}\Rightarrow x=8.3:12=2\)

e,\(\frac{2}{3}-1\frac{4}{15}x=-\frac{3}{5}\Rightarrow1\frac{4}{15}x=\frac{2}{3}+\frac{3}{5}\Rightarrow\frac{19}{15}x=\frac{19}{15}\Rightarrow x=1\)

f,\(-2^3+0,5x=1,5\Rightarrow-8+0,5x=1,5\Rightarrow0,5x=1,5+8\)

\(\Rightarrow0,5x=9,5\Rightarrow x=19\)

g,\(2^{x-1}=16\Rightarrow x-1=4\Rightarrow x=5\)

Bài 2:

1) \(\frac{x}{12}-\frac{5}{6}=\frac{1}{12}\)

\(\Rightarrow\frac{x}{12}=\frac{1}{12}+\frac{5}{6}\)

\(\Rightarrow\frac{x}{12}=\frac{11}{12}\)

\(\Rightarrow x.12=11.12\)

\(\Rightarrow x.12=132\)

\(\Rightarrow x=132:12\)

\(\Rightarrow x=11\)

Vậy \(x=11.\)

2) \(\frac{2}{3}-1\frac{4}{15}x=\frac{-3}{5}\)

\(\Rightarrow\frac{2}{3}-\frac{19}{15}x=\frac{-3}{5}\)

\(\Rightarrow\frac{19}{15}x=\frac{2}{3}+\frac{3}{5}\)

\(\Rightarrow\frac{19}{15}x=\frac{19}{15}\)

\(\Rightarrow x=\frac{19}{15}:\frac{19}{15}\)

\(\Rightarrow x=1\)

Vậy \(x=1.\)

3) \(\left(-2\right)^3+0,5x=1,5\)

\(\Rightarrow-8+0,5x=1,5\)

\(\Rightarrow0,5x=1,5+8\)

\(\Rightarrow0,5x=9,5\)

\(\Rightarrow x=9,5:0,5\)

\(\Rightarrow x=19\)

Vậy \(x=19.\)

Chúc bạn học tốt!

\(\hept{\begin{cases}\text{|}0,5x\text{|}=0,5x\\\sqrt{\left(0,5x\right)^2}=0,5x\\\left(0,5x\right)^2=\left(0,5x\right)^2\end{cases}}\)

2, tương tự

\(\hept{\begin{cases}\text{|}-\frac{2}{3}x\text{|}=\frac{2}{3}x\\\sqrt{\left(-\frac{2}{3}x\right)^2}=\frac{2}{3}x\\\left(-\frac{2}{3}x\right)^2=\left(\frac{2}{3}x\right)^2\end{cases}}\)

4, tương tự 

Đây là những bài cơ bản mà bạn!

\(\frac{5x-2}{3}=\frac{5-3x}{2}\)

\(< =>\frac{\left(5x-2\right).2}{6}=\frac{\left(5-3x\right).3}{6}\)

\(< =>\left(5x-2\right).2=\left(5-3x\right).3\)

\(< =>10x-4=15-9x\)

\(< =>10x+9x=15+4\)

\(< =>19x=19< =>x=1\)

\(\frac{10x+3}{12}=1+\frac{6+8x}{9}\)

\(< =>\frac{\left(10x+3\right).3}{36}=\frac{36}{36}+\frac{\left(6+8x\right).4}{36}\)

\(< =>\left(10x+3\right).3=36+\left(6+8x\right).4\)

\(< =>30x+9=36+24+32x\)

\(< =>32x-30x=9-36-24\)

\(< =>2x=9-60=-51< =>x=-\frac{51}{2}\)

Tìm x:

a)-2³+0,5x=1,5

-8+0,5x = 1,5

0,5x = 1,5-(-8) = 9,5

x = 9,5:0,5 = 19

b)(−3)x81=−27

(-3)^x:81 =-27

(-3)^x = -27.81 = -2187

(-3)^x = (-3)⁷

=> x=7

c)112.x−4=0,5

1,5.x = 0,5+4 = 4,5

x = 4,5:1,5 = 3

d)123:x4=6:0,3

\(\frac{5}{3}\):\(\frac{x}{4}\) = 20

\(\frac{x}{4}\) = \(\frac{5}{3}\):20 = \(\frac{1}{12}\)

=> x:4 = \(\frac{1}{12}\)

x = \(\frac{1}{12}\).4 = \(\frac{1}{3}\)

Bài 1:

d)

= \(\frac{-5}{9}\left(\frac{6}{13}+\frac{7}{13}\right)+\frac{5}{23}.\frac{7}{9}\)

= \(\frac{-5}{9}.1+\frac{35}{207}\)

= \(\frac{-80}{207}\)

Bài 2:

a) 20%x + 0,4x = 4,5

x( 20% + 0,4 ) = 4,5

x. 0,6 = 4,5

x = 4,5 : 0,6

x = 7,5

a. \(0,5x-\frac{1}{3}x=\frac{1}{3}\)

 \(\left(0,5-\frac{1}{3}\right)x=\frac{1}{3}\)

                   \(\frac{1}{6}x=\frac{1}{3}\)

                         \(x=\frac{1}{3}:\frac{1}{6}\)

                        \(x=2\)

b. \(x:3\frac{1}{2}=-1,5\)

           \(x=-1,5\times3\frac{1}{2}\)

           \(x=-5,25\)

c. \(1,5x=\frac{11}{5}\)

          \(x=\frac{22}{15}\)

A. 0,5x - 1/3x = 1/3

    (0,5 - 1/3)x = 1/3

              1/6x = 1/3

                  x = 2

B. x : 3 1/2 = -1,5

              x = -1,5 x 3 1/2

              x = -5,25

C. 1,5x = 11/5

        x = 22/15

22/15 nha bn