a) \(70-5\left(2x-3\right)=45\)

\(70-10x+15=45\)

\(-10x=45-70-15\)

\(-10x=-40\)

\(x=4\)

vay \(x=4\)

 b) \(156-\left(x+61\right)=82\)

\(x+61=156-82\)

\(x+61=74\)

\(x=74-61\)

\(x=13\)

vay \(x=13\)

c) \(6\left(5x+35\right)=330\)

\(30x+210=330\)

\(30x=330-210\)

\(30x=120\)

\(x=4\)

vay \(x=4\)

d) \(936-\left(4x+24\right)=72\)

\(4x+24=936-72\)

\(4x+24=864\)

\(4x=864-24\)

\(4x=840\)

\(x=210\)

vay \(x=210\)

\(70-5.\left(2x-3\right)\)\(=45\)

\(5.\left(2x-3\right)\)\(=\)\(70-45\)

\(5.\left(2x-3\right)\)\(=25\)

\(2x-3=25:5\)

\(2x-3=5\)

\(2x=8\)

\(x=8:2\)

\(x=4\)

\(156-\left(x+61\right)\)\(=82\)

\(x+61=156-82\)

\(x+61=74\)

\(x=74-61\)

\(x=13\)

\(6.\left(5x+35\right)\)\(=330\)

\(5x+35=330:6\)

\(5x+35=55\)

\(5x=55-35\)

\(5x=20\)

\(x=20:5\)

\(x=4\)

\(936-\left(4x+24\right)\)\(=72\)

\(4x+24=936-72\)

\(4x+24=864\)

\(4x=864-24\)

\(4x=840\)

\(x=840:4\)

\(x=210\)

Tìm x :

a) 70 - 5 . ( 2x - 3 ) = 45

           5 . ( 2x - 3 ) = 70 - 45

           5 . ( 2x - 3 ) = 25

                    2x - 3 = 25 : 5

                    2x - 3 = 5

                         2x = 5 + 3

                         2x = 8

                           x = 8 : 2

                           x = 4

b)    156 - ( x + 61 ) = 82

                     x + 61 = 156 - 82

                     x + 61 =  74

                             x = 74 - 61

                             x = 13

c) 6 . ( 5x + 35 ) = 330

             5x + 35 = 330 : 6

             5x + 35 = 55

                     5x = 55 - 35

                     5x = 20

                       x = 20 : 5 

                       x = 4

d) 936 - ( 4x + 24 ) = 72

                  4x + 24 = 936 - 72

                  4x + 24 = 364

                          4x = 364 - 24

                          4x = 340

                            x = 340 : 4

                            x = 85

Giải:

a) \(\dfrac{-5}{8}=\dfrac{x}{16}\) 

\(\Rightarrow x=\dfrac{16.-5}{8}=-10\) 

\(\dfrac{3x}{9}=\dfrac{2}{6}\) 

\(\Rightarrow3x=\dfrac{2.9}{6}=3\) 

\(\Rightarrow x=1\)

b) \(\dfrac{x+3}{15}=\dfrac{1}{3}\)  

\(\Rightarrow x+3=\dfrac{1.15}{3}=5\) 

\(\Rightarrow x=2\)

\(\dfrac{6}{2x+1}=\dfrac{2}{7}\) 

\(\Rightarrow2x+1=\dfrac{6.7}{2}=21\) 

\(\Rightarrow x=10\)

c) \(\dfrac{4}{x-6}=\dfrac{y}{24}=\dfrac{-12}{18}\) 

\(\Rightarrow\dfrac{4}{x-6}=\dfrac{-12}{18}\) 

\(\Rightarrow x-6=\dfrac{18.4}{-12}=-6\) 

\(\Rightarrow x=0\) 

\(\Rightarrow\dfrac{y}{24}=\dfrac{-12}{18}\) 

\(\Rightarrow y=\dfrac{-12.24}{18}=-16\) 

 \(\dfrac{3-x}{-12}=\dfrac{16}{y+1}=\dfrac{192}{-72}\) 

\(\Rightarrow\dfrac{3-x}{-12}=\dfrac{192}{-72}\) 

\(\Rightarrow3-x=\dfrac{192.-12}{-72}=32\) 

\(\Rightarrow x=-29\) 

\(\Rightarrow\dfrac{16}{y+1}=\dfrac{192}{-72}\) 

\(\Rightarrow y+1=\dfrac{16.-72}{192}=-6\) 

d) \(\dfrac{-2}{3}< \dfrac{x}{5}< \dfrac{-1}{6}\) 

\(\Rightarrow\dfrac{-20}{30}< \dfrac{6x}{30}< \dfrac{-5}{30}\) 

\(\Rightarrow6x\in\left\{-18;-12;-6\right\}\) 

\(\Rightarrow x\in\left\{-3;-2;-1\right\}\) 

\(\dfrac{-1}{5}\le\dfrac{x}{8}\le\dfrac{1}{4}\) 

\(\Rightarrow\dfrac{-8}{40}\le\dfrac{5x}{40}\le\dfrac{10}{40}\) 

\(\Rightarrow5x\in\left\{-5;0;5;10\right\}\) 

\(\Rightarrow x\in\left\{-1;0;1;2\right\}\) 

e) \(\dfrac{x+46}{20}=x\dfrac{2}{5}\) 

\(\Rightarrow\dfrac{x+46}{20}=x+\dfrac{2}{5}\) 

\(\Rightarrow\dfrac{x+46}{20}=\dfrac{5x+2}{5}\) 

\(\Rightarrow5.\left(x+46\right)=20.\left(5x+2\right)\) 

\(\Rightarrow5x+230=100x+40\) 

\(\Rightarrow5x-100x=40-230\) 

\(\Rightarrow-95x=-190\) 

\(\Rightarrow x=-190:-95\) 

\(\Rightarrow x=2\) 

\(y\dfrac{5}{y}=\dfrac{86}{y}\) 

\(\Rightarrow y+\dfrac{5}{y}=\dfrac{86}{y}\) 

\(\Rightarrow\dfrac{y^2+5}{y}=\dfrac{86}{y}\) 

\(\Rightarrow y^2+5=86\) 

\(\Rightarrow y^2=86-5\) 

\(\Rightarrow y^2=81\) 

\(\Rightarrow\left[{}\begin{matrix}y=9\\y=-9\end{matrix}\right.\) 

Chúc bạn học tốt!

a: Ta có: \(4\left(2-x\right)+x\left(x+6\right)=x^2\)

\(\Leftrightarrow8-4x+x^2+6x-x^2=0\)

\(\Leftrightarrow2x=-8\)

hay x=-4

b: Ta có: \(x\left(x-7\right)-\left(x-2\right)\left(x+5\right)=0\)

\(\Leftrightarrow x^2-7x-x^2-3x+10=0\)

\(\Leftrightarrow-10x=-10\)

hay x=1

c: Ta có: \(\left(2x+3\right)\left(3-2x\right)+\left(2x-1\right)^2=2\)

\(\Leftrightarrow9-4x^2+4x^2-4x+1=2\)

\(\Leftrightarrow-4x=-8\)

hay x=2

a: Ta có: \(3\left(2x-3\right)+2\left(2-x\right)=-3\)

\(\Leftrightarrow6x-9+4-2x=-3\)

\(\Leftrightarrow4x=2\)

hay \(x=\dfrac{1}{2}\)

a, \(231-\left(x-6\right)=1339:13\)

\(\Leftrightarrow231-\left(x-6\right)=103\)

\(\Leftrightarrow x-6=128\)

\(\Leftrightarrow x=134\)

Vậy .....

b, \(70-5\left(2x-3\right)=45\)

\(\Leftrightarrow5\left(2x-3\right)=25\)

\(\Leftrightarrow2x-3=5\)

\(\Leftrightarrow2x=8\)

\(\Leftrightarrow x=4\)

Vậy ....

c, \(156-\left(x+61\right)=82\)

\(\Leftrightarrow x+61=74\)

\(\Leftrightarrow x=13\)

Vậy ....

d, \(6\left(5x+35\right)=330\)

\(\Leftrightarrow5x+35=55\)

\(\Leftrightarrow5x=20\)

\(\Leftrightarrow x=4\)

Vậy ......

e, \(936-\left(4x+24\right)=72\)

\(\Leftrightarrow4x+24=864\)

\(\Leftrightarrow4x=840\)

\(\Leftrightarrow x=210\)

Vậy ...

231-(x-6)=1339:13

237-x=103

=>x=237-103=134

Vậy x=134

70-5(2x-3)=45

70-10x+15=45

=>-10x=45-15-70=-40

=>x=4

Vậy x=4

Các caau sau tương tự nhé bn

a, 231 - ( x - 6 ) = 1339 : 13

231 - ( x -6 ) = 103

x - 6 = 231 - 103 = 128

x = 128 + 6 = 134

b, 70 - 5 (2x -3 ) = 45

5 ( 2x -3 ) = 70 - 45 = 25

( 2x -3 ) = 25 : 5 = 5

2x = 5 + 3 = 8

x = 8 : 2 = 4

c, 156 - ( x + 61 ) = 82

x + 61 = 156 - 82 =74

x = 74 - 61

x = 13

d, 6 ( 5x + 35 ) = 330

5x + 35 = 330 : 6 = 55

5x = 55 - 35 = 20

x = 20 : 5 = 4

e, 936-(4x+ 24 ) = 72

4x + 24 = 936 - 72 = 864

4x = 864 - 24 = 840

x = 840 : 4 = 210

Chuc ban hoc tot nhe

tách đi bạn

a) (2x - 3)(6 - 2x) = 0

=> \(\left[{}\begin{matrix}2x-3=0\\6-2x=0\end{matrix}\right.=>\left[{}\begin{matrix}2x=3\\2x=6\end{matrix}\right.=>\left[{}\begin{matrix}x=\dfrac{3}{2}\\x=3\end{matrix}\right.\)

b) \(5\dfrac{4}{7}:x=13=>\dfrac{39}{7}:x=13=>x=\dfrac{39}{7}:13=>x=\dfrac{3}{7}\)

c) \(2x-\dfrac{3}{7}=6\dfrac{2}{7}=>2x-\dfrac{3}{7}=\dfrac{44}{7}=>2x=\dfrac{47}{7}=>x=\dfrac{47}{14}\)

d) \(\dfrac{x}{5}+\dfrac{1}{2}=\dfrac{6}{10}=>\dfrac{x}{5}=\dfrac{6}{10}-\dfrac{1}{2}=>\dfrac{x}{5}=\dfrac{1}{10}=>x.10=5=>x=\dfrac{1}{2}\)

e) \(\dfrac{x+3}{15}=\dfrac{1}{3}=>\left(x+3\right).3=15=>x+3=5=>x=2\)

f)\(\dfrac{x-12}{4}=\dfrac{1}{2}=\dfrac{x-12}{4}=\dfrac{2}{4}\)

⇒\(x-12=2\)

   \(x=2+12\)

  x = 14

g)2\(\dfrac{1}{4}.\left(x-7\dfrac{1}{3}\right)=1,5\)

\(\dfrac{9}{4}.\left(x-\dfrac{22}{3}\right)=1,5\) 

      \(\left(x-\dfrac{22}{3}\right)=\dfrac{3}{2}:\dfrac{9}{4}\)

       \(x-\dfrac{22}{3}=\dfrac{2}{3}\)

       \(x=\dfrac{2}{3}+\dfrac{22}{3}\) 

      \(x=8\)

a) x = 15

b) x = 11

c) x = 68

d) x = 310

(x4)3=x6x19

a) x = 15.              b)      x = 11.        c) x = 68.              d) x = 310

Tìm xx biết:    \left(x^{4}\right)^{3}=\dfrac{x^{19}}{x^{6}}(x4)3=x6x19​

Trả lời: x=x=