Question

Tìm x, biết:

a, 12+x =-14

b, 60 - (5x - 5) = 45

c, |15 + 3x| = 3². 5

Giải chi tiết giúp mk nha:))

Answer 1

a)12+x=-14

         x=-14-12

         x=-26

vậy x=-26

b)60-(5x-5)=45

5x-5=60-45

5x-5=15

5x=15:5

  5x=3

    x=\(\frac{3}{5}\)

vậy \(x=\frac{3}{5}\)

c)|15+3x|=3².5

|15+3x|=9.5

|15+3x|=45

* 15+3x=45            * 15+3x=-45

   3x=45-15               3x=-45-15

   3x=30                    3x=-60

     x=30:3                   x=-60:3

     x=10                      x=-20

vậy x=10 hoặc x=-20

Answer 2

a, 12 + x = -14

=> x = -14 - 12

=> x = -26

b, 60 - ( 5x - 5 ) = 45

=> 5x - 5 = 60 - 45

=> 5x - 5 = 15

=> 5x = 20

=> x = 4

c, | 15 + 3x | = 3². 5

=> | 15 + 3x | = 45

\(\Rightarrow\orbr{\begin{cases}15+3x=45\\15+3x=-45\end{cases}\Leftrightarrow\orbr{\begin{cases}3x=30\\3x=-60\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=10\\x=-20\end{cases}}}\)

Answer 3

a, 12 + x = -14

x= -14-12

x= -26

b, 60-(5x-5) = 45

5x-5 = 60 -45

5x-5 = 15

5x = 15+5 

5x  = 20

x =20:5

x = 4

c, I15 + 3x I = 3^2 . 5

I15 +3xI = 9.5

I15+3xI = 45 

TH1, 15+3x = 45

3x = 45 - 15

3x= 30

 x= 30:3

x=10

TH2, 15+3x = -45

3x = -45-15

3x = - 60

x =-60 : 3

x= -20

Vậy ................................................................................................

hk tốt

Answer 4

a)12+x=-14

         x=-14 - 12

         x=-26

b)60 - (5x - 5) = 45

5x - 5 = 60 - 45

5x - 5 = 15

5x = 15 + 5

5x = 20

x=20 : 5

x = 4

c)|15 + 3x| = 3² . 5

|15 + 3x| = 9 . 5

|15 + 3x| = 45

Th1:

15 + 3x=45

3x = 45 - 15

3x = 30

x = 30 : 3

x = 10

Th2:

15 + 3x = -45

3x = -45 - 15

3x = -60

x = -60 : 3

x = -20

Học tốt!

Answer 5

b)60-(5x-5)=45

5x-5=60-45

5x-5=15

5x=15+5

5x=20

  x=20:5

  x=4

vậy x=4

Answer 6

Cảm ơn tất cả các bn nha:))

Answer 7

a)12+x=-14

=>x=(-14)-12

=>x=-26

b)60-(5x-5)=45

=>5x-5=60-45

=>5x-5=15

=>5x=15+5

=>5x=20

=>x=20:5

=>x=4

c)|15+3x|=3^2.5

=>|15+3x|=45

\(\Rightarrow\orbr{\begin{cases}15+3x=45\\15+3x=-45\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}3x=30\\3x=-60\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=10\\x=-20\end{cases}}\)

VẬY \(x\in\left\{10,-20\right\}\)

Đúng thì k nhé

Answer 8

a,12+x=-14\(\Rightarrow\)x=-14-12\(\Rightarrow\)x=-26

b,60-(5x-5)=45\(\Rightarrow\)5x-5=15\(\Rightarrow\)5x=20\(\Rightarrow\)x=4

c,|15+3x|=3^2*5\(\Rightarrow\)|15-3x|=45\(\Rightarrow\)15-3x=45\(\Rightarrow\)3x=-30\(\Rightarrow\)x=-10

                                                               15-3x=-45\(\Rightarrow\)3x=60\(\Rightarrow\)x=20

Answer 9

a) 12 + x = -14

            x = -14 - 12

            x = -26

b) 60 - (5x - 5) = 45

        5x - 5       = 60 - 45

        5x - 5       = 15

          5x          = 15 + 5

          5x          = 20

           x           = 20 : 5

           x           = 4

c) | 15 + 3x | = 3² . 5

    | 15 + 3x | = 9 . 5

    | 15 + 3x | = 45

\(\Rightarrow\orbr{\begin{cases}15+3x=45\\15+3x=-45\end{cases}}\Rightarrow\orbr{\begin{cases}3x=45-15=30\\3x=\left(-45\right)-15=60\end{cases}}\Rightarrow\orbr{\begin{cases}x=30\div3=10\\x=\left(-60\right)\div3=-20\end{cases}}\)

Answer 10

                                                                 Bài giải

a, \(12+x=-14\)

\(x=-14-12\)

\(x=-26\)

b, \(60-\left(5x-5\right)=45\)

\(5x-5=60-45\)

\(5x-5=15\)

\(5x=15+5\)

\(5x=20\)

\(x=20\text{ : }5\)

\(x=4\)

c, \(\left|15+3x\right|=3^2\cdot5\)

\(\left|15+3x\right|=9\cdot5\)

\(\left|15+3x\right|=45\)

\(\Rightarrow\orbr{\begin{cases}15+3x=-45\\15+3x=45\end{cases}}\Rightarrow\orbr{\begin{cases}3x=-60\\3x=30\end{cases}}\Rightarrow\orbr{\begin{cases}x=-20\\x=10\end{cases}}\)

\(\Rightarrow\text{ }x\in\left\{-20\text{ ; }10\right\}\)