\(\left[\left(4x+28\right).3+55\right]:5=35\)

\(\Rightarrow\left(4x+28\right).3+55=35.5\)

\(\Rightarrow\left(4x+28\right).3+55=175\)

\(\Rightarrow\left(4x+28\right).3=175-55\)

\(\Rightarrow\left(4x+28\right).3=120\)

\(\Rightarrow4x+28=120:3\)

\(\Rightarrow4x+28=40\)

\(\Rightarrow4x=40-28\)

\(\Rightarrow4x=12\)

\(\Rightarrow x=12:4\)

\(\Rightarrow x=3\)

[ ( 4x + 28 ). 3 + 55 ] ÷ 5 = 35

( 4x + 28 ). 3 + 55 = 35.5

( 4x + 28 ). 3 + 55 = 175

( 4x + 28 ). 3 = 175 - 55

( 4x + 28 ). 3 = 120

4x + 28 = 120 : 3

4x + 28 = 40

4x = 40 - 28

4x = 12

x = 12 : 4

x = 3

\(\left\{\left[3^{14}.69+12.3^{14}\right]:3^{16}-7\right\}:2^4\)

\(=\left\{\left[3^{14}.\left(69+12\right)\right]:3^{16}-7\right\}:16\)

\(=\left\{\left[3^{14}.81\right]:3^{16}-7\right\}:16\)

\(=\left\{\left[3^{14}.3^4\right]:3^{16}-7\right\}:16\)

\(=\left\{3^{18}:3^{16}-7\right\}:16\)

\(=\left\{3^2-7\right\}:16\)

\(=\left\{9-7\right\}:16\)

\(=2:16\)

\(=\frac{1}{8}\)

/x/=20-13

/x/=7

x=+-7

nha

|7|+13=20

\(\left|x\right|+13=20\)

\(\Rightarrow\left|x\right|=20-13\)

\(\Rightarrow\left|x\right|=7\)

\(\Rightarrow\orbr{\begin{cases}x=7\\x=-7\end{cases}}\)

/x/=20-13

/x/=7

x=+-7

dấu suy ra trước x nha.  

Ta có:

\(A=\frac{2^{18}.18^7.3^3+3^{15}.2^{15}}{2^{10}.6^{15}+3^{14}.15.4^{13}}=\frac{2^{18}.\left(2.3^2\right)^7.3^3+3^{15}.2^{15}}{2^{10}.\left(2.3\right)^{15}+3^{14}.3.5.\left(2^2\right)^{13}}\)

\(=\frac{2^{18}.2^7.3^{14}.3^3+3^{15}.2^{15}}{2^{10}.2^{15}.3^{15}+3^{15}.5.2^{16}}=\frac{2^{25}.3^{17}+2^{15}.3^{15}}{2^{25}.3^{15}+3^{15}.2^{16}.5}=\frac{2^{15}.3^{15}.\left(3^2.2^{10}+1\right)}{2^{16}.3^{15}.\left(2^9+5\right)}\)

\(=\frac{3^2.2^{10}+1}{2^{10}+10}=\frac{9.1024+1}{1024+10}=\frac{9217}{1025}\)