X+7= -89

X= -89 - 7

X= -96

x+7=135-(135+89)

=>x+7=135-135-89

=>x+7=0-89=-89

=>x=-89-7

=>x=-96

x + 7 = 135 - 135 - 89

x + 7 = 0 -89

x + 7 = -89

     x= -89 - 7

     x= -96

b) -26 - ( x - 7 ) = 0

               x - 7   = -26 - 0

                x - 7  = -26

                x        = -26 + 7

                 x       = -19

Bài 2 :

a) 3 - ( 17 - x ) = -12

          ( 17 - x ) = 3 - ( -12 )

          ( 17 - x ) = 15

                    x  = 17 - 15

                    x  = 2

b) -26 - ( x - 7)=0

             x - 7 = -26 -0

            x - 7 = -26

              x = -26 + 7

             x = -19

a. X  x 7 = 4907

X =  4907 : 7

 X =  701

b.  X  :  4  =  135

X   = 135 x 4

X   =  540

Mk giải câu 1 nha

1) 2x - 3 = x + 1/2

➡️2x - x = 1/2 + 3

➡️x        = 7/2

Hok tốt~

\(\dfrac{3}{x-7}=\dfrac{27}{135}\)

\(27\times\left(x-7\right)=3\times135\)

\(27\times x-189=405\)

\(27\times x=405+189\)

\(27\times x=594\)

\(x=594\div27\)

\(x=22\)

3/(x - 7) = 27/135

3 × 135 = (x - 7) × 27

(x - 7) × 27 = 405

x - 7 = 405 : 27

x - 7 = 15

x = 15 + 7

x = 22

@kiều vũ linh theo đề thì ta phải có:

\(3\cdot135=27\cdot\left(x-7\right)\)

3/x-7 = 27/135

3/x-7 = 3/15

x - 7 = 15

x = 15 + 7

x = 22

135⁹¹ - 135⁸⁹ = 135⁸⁹ x ( 135² - 1 ) 

135¹⁰⁰ - 135⁹⁹ = 135⁹⁹ x ( 135 - 1 ) = 135⁹⁹ x 134 = 135⁸⁹ x 135¹⁰ x 134 = 135⁸⁹ x  ( 135¹⁰ x 134 )

Có : 135² - 1 < 135¹⁰ x 134

=> 135⁸⁹ x ( 135² - 1 ) < 135⁸⁹ x ( 135¹⁰ x 134 )

=> 135⁹¹ - 135⁸⁹ < 135¹⁰⁰ - 135⁹⁹

Ta có:

\(135^{91}-135^{89}=135^{89}\times\left(135^2-1\right)\)

\(135^{100}-135^{99}=135^{99}\times\left(135-1\right)=135^{99}\times134=135^{89}\times134=135^{89}\times\left(135^{10}\times34\right)\)

Có: \(135^2-1< 135^{10}\times134\)

\(\Rightarrow135^{89}\times\left(135^2-1\right)< 135^{89}\times\left(135^{10}\times134\right)\)

\(\Rightarrow135^{91}-135^{89}< 135^{100}-135^{99}\)

Vậy \(135^{91}-135^{89}< 135^{100}-135^{99}\)

Chọn D