a) \(123-5\left(x+4\right)=38\)

\(5\left(x+4\right)=123-38\)

\(5\left(x+4\right)=85\)

\(x+4=85:5\)

\(x+4=17\)

\(x=17-4\)

\(x=13\)

Vậy \(x=13\).

b) \(\left(3x-2^4\right)\cdot7^3=2\cdot7^4\)

\(3x-16=2\cdot7^4:7^3\)

\(3x-16=2\cdot7\)

\(3x-16=14\)

\(3x=14+16\)

\(3x=30\)

\(x=30:3\)

\(x=10\)

Vậy \(x=10\).

a) GTNN = 0 khi x = -1

b) GTNN = 503 khi x =0

a: \(A=\dfrac{63-48-70}{84}:\dfrac{-3\cdot84+4\cdot60+5\cdot70}{840}\cdot\dfrac{1-14}{12}\)

\(=\dfrac{-55}{84}\cdot\dfrac{840}{338}\cdot\dfrac{-13}{12}=\dfrac{55}{1}\cdot\dfrac{10}{338}\cdot\dfrac{13}{12}=\dfrac{275}{156}\)

b: \(=-234\cdot123+123\cdot4356-123\cdot2312+234\cdot123-234\cdot2312+2312\cdot234+2312\cdot123\)

\(=123\cdot4356-123\cdot2312+123\cdot2312=123\cdot4356=535788\)

\(123-5\left(x+4\right)=38\\ 5\left(x+4\right)=85\\ x+4=17\\ x=13\)

\(123-5\left(x+4\right)=38\)

\(\Rightarrow123-5x-20=38\)

\(\Rightarrow-5x=-65\)

\(\Rightarrow x=13\)

Vậy: ...

\(123-5x-20=38\Leftrightarrow123-5x=58\Leftrightarrow5x=65\Leftrightarrow x=13\)

`123-5(x+4)=38`

`5x-20=123-38`

`5x-20=85`

`5x=85+20`

`5x=105`

`x=105:5`

`x=21`

123-5.(x+4)=38

         5x-20=123-38

         5x-20=85

               5x=85+20

               5x=105

                 x=105:5

                x=21

\(123-5\left(x:2+4\right)=38\\ \Rightarrow5\left(x:2+4\right)=85\\ \Rightarrow x:2+4=17\\ \Rightarrow x:2=13\\ \Rightarrow x=26.\)

\(123-5\left(x:2+4\right)=38\)

\(5\left(x:2+4\right)=123-38\)

\(5\left(x:2+4\right)=85\)

\(x:2+4=85:5\)

\(x:2+4=17\)

\(x:2=17-4\)

\(x:2=13\)

\(x=13.2\)

\(x=26\)

\(123-5\left(x:2+4\right)=38\\ 5\left(x:2+4\right)=85\\ x:2+4=17\\ x:2=13\\ x=26\)

\(a,\left(\frac{2}{5}\right)^6.\left(\frac{25}{4}\right)^2=\left(\frac{2}{2.3}\right)^6.\left(\frac{5}{2}\right)^4\)

\(=\frac{1}{3^6}.\frac{5^4}{2^4}=\frac{5^4}{3^6.2^4}\)

\(b,\frac{100}{123}:\left(\frac{3}{4}+\frac{7}{12}\right)+\frac{23}{123}:\left(\frac{9}{5}-\frac{7}{15}\right)\)

\(=\frac{100}{123}:\left(\frac{9+7}{12}\right)+\frac{23}{123}:\left(\frac{27-7}{15}\right)\)

\(=\frac{100}{123}:\frac{16}{12}+\frac{23}{123}:\frac{20}{15}\)

\(=\frac{100.12}{123.16}+\frac{23.15}{123.20}\)

\(=\frac{5.5.4.3.4}{41.3.4.4}+\frac{23.3.5}{41.3.4.5}\)

\(=\frac{25}{41}+\frac{23}{164}=\frac{25.4+23}{164}\)

\(=\frac{123}{164}=\frac{3}{4}\)

123 - 5 . ( x + 4 ) = 38

5 . ( x + 4 ) = 123 - 38

5 . ( x + 4 ) = 85

x + 4 = 85 : 5

x + 4 = 17

      x = 17 - 4

 => x = 13

123-5.(x+4)=38

=>5.(x-4)=123-38

=>5.(x-4)=85

=>x-4=85:5

=>x-4=17

=>x=17+4

=>x=21

123-5 . (x+4) =38

5.(x+4)=123-38

5.(x+4)=85

x+4=85:5

x+4=17

x=17-4

x=13