123-x=123.(12-1)

123-x=123.11

123-x=1353

        x=1353:123

        x=11

vậy x=11

Bài làm

123 - x = 123 . ( 12 - 1 )

123 - x = 123 . 11

123 - x = 1353

         x = 123 - 1353

         x = -1230

Vậy x = -1230

# Học tốt #

123 - x = 123 . (12 - 1)

123 - x = 123 . 11

123 - x = 1353

         x = 1353 - 123

         x = 1230

\(a,123\times54+27\times123-12\times123+123\times31\)

\(=123\times\left(54+27-12+31\right)\)

\(=123\times100\)

\(=12300\)

\(b,\dfrac{121}{27}\times\dfrac{54}{11}< n< \dfrac{100}{21}:\dfrac{25}{126}\)

\(22< n< \dfrac{100}{21}\times\dfrac{126}{25}\)

\(22< n< 24\)

Vì \(23>22\) và \(23< 24\) nên \(n=23\)

a, 123x(54+27-12+31)

=123x100

=12300

a123x54+27x123-12x123+123x31

=123:54+27:123-12:123+123:31

=6642+27:123-12:123+123:31

=6642+3321-12:123+123:31

=6642+3321-1476+123:31

=6642+3321-1476+3813

=12300

b,121/27x54/11<n>100/21:25/126

=22<n>24

n=23

\(a,123:x+12:x=4,5\\ \Rightarrow\left(123+12\right):x=4,5\\ \Rightarrow135:x=4,5\\ \Rightarrow x=30\\ b,89:x-5,15:x=62,5\\ \Rightarrow\left(89-5,15\right):x=62,5\\ \Rightarrow83,85:x=62,5\\ \Rightarrow x=1,3416\)

\(a,\Rightarrow\left(123+12\right):x=4,5\\ \Rightarrow135:x=4,5\\ \Rightarrow x=135:4,5=30\\ b,\Rightarrow\left(89-5,15\right):x=62,5\\ \Rightarrow83,85:x=62,5\\ \Rightarrow x=83,85:62,5=1,3416\)

a) x-12=-15
x=-15+12
x=-3
b) 123-5(x+4)=38
5(x+4)=123-38
5(x+4)=85
x+4=85:5=17
x=17-4
x=13

\(a.x-12=-15\)                    \(b.123-5.\left(x+4\right)=38\)

\(x=\left(-15\right)+12\)                        \(5.\left(x+4\right)=123-38\)

\(x=-3\)                                      \(5.\left(x+4\right)=85\)           

                                                   \(x+4=85:5=17\)

                                                    \(x=17-4=13\)

a) x-12=-15
x=-15+12
x=-3
b) 123-5(x+4)=38
5(x+4)=123-38
5(x+4)=85
x+4=85:5=17
x=17-4
x=13

b)\(7\times x-3\times x=123\)

\(x\times\left(7-3\right)=123\)

\(x\times4=123\)

\(x=123\div4\)

\(x=30,75\)

Ta có: \(\frac{x}{2}+3\times x=12\)

\(x\times\frac{1}{2}+3\times x=12\)

\(x\times\left(\frac{1}{2}+3\right)=12\)

\(x\times\frac{7}{2}=12\)

\(x=12\div\frac{7}{2}\)

\(x=\frac{24}{7}\)

3.428571429

30,75

|x+23|^2002|+|y-12|^123=0

<=>|x+23|^2002\(\ge\) 0

      \(\left|y-12\right|^{^{123}}\ge0\)

=>\(\left|x+23\right|^{2002}+\left|y-12\right|^{123}\ge0\)

=>x+23=0=>x=-23

=>y-12=0=>y=12

\(\left|x+23\right|^{2002}+\left|y-12\right|^{123}=0\)

\(\Rightarrow\hept{\begin{cases}\left|x+23\right|^{2002}=0\\\left|y-12\right|^{123}=0\end{cases}}\Rightarrow\hept{\begin{cases}x+23=0\\y-12=0\end{cases}}\Rightarrow\hept{\begin{cases}x=-23\\y=12\end{cases}}\)

Vậy \(x=-23;y=12\)

Vì \(\left|x+23\right|^{2002}\ge0;\left|y-12\right|^{123}\ge0\forall x;y\)

\(\Rightarrow\left|x+23\right|^{2002}+\left|y-12\right|^{123}\ge0\forall x;y\)

Mà đề lại cho \(\left|x+23\right|^{2002}+\left|y-12\right|^{123}=0\)

\(\Leftrightarrow\left|x+23\right|^{2002}=0;\left|y-12\right|^{123}=0\)

\(\Rightarrow x=-23;y=12\)

a) \(5\times x-123=12\)

\(\Rightarrow5\times x=135\)

\(\Rightarrow x=27\)

b) \(x+3x+5x+7x=96\)

\(\Rightarrow16x=96\)

\(\Rightarrow x=6\)

a) \(5\times x-123=12\)

\(5x=12+123\)

\(5x=135\)

\(x=135:5\)

\(x=27\)

________

b) \(x+3x+5x+7x=96\)

\(x\left(1+3+5+7\right)=96\)

\(x.16=96\)

\(x=96:16\)

\(x=6\)

a)

\(5\times x-123=12\\\Rightarrow 5\times x=12+123\\\Rightarrow 5\times x=135\\\Rightarrow x=135:5\\\Rightarrow x=27\\---\)

b) 

\(x+3x+5x+7x=96\\\Rightarrow16x=96\\\Rightarrow x=96:16\\\Rightarrow x=6\)