Решите уравнение: 1) 1 - 2(5 + 3x) = 15; 2) (9 - 10x) - (5x - 2) = 20; 3) 3(2 - 3x) + 20 + 3x = 2; 4) 4x - 6 = 5x - 2(2x - 9).

Решение:

1. 
   

   \( 1 - 2(5 + 3x) = 15 \)

   
   

   \( 1 - 10 - 6x = 15 \)

   
   

   \( -9 - 6x = 15 \)

   
   

   \( -6x = 15 + 9 \)

   
   

   \( -6x = 24 \)

   
   

   \( x = \frac{24}{-6} \)

   
   

   \( x = -4 \)

   
   


2. 
   

   \( (9 - 10x) - (5x - 2) = 20 \)

   
   

   \( 9 - 10x - 5x + 2 = 20 \)

   
   

   \( 11 - 15x = 20 \)

   
   

   \( -15x = 20 - 11 \)

   
   

   \( -15x = 9 \)

   
   

   \( x = \frac{9}{-15} \)

   
   

   \( x = -\frac{3}{5} \)

   
   


3. 
   

   \( 3(2 - 3x) + 20 + 3x = 2 \)

   
   

   \( 6 - 9x + 20 + 3x = 2 \)

   
   

   \( 26 - 6x = 2 \)

   
   

   \( -6x = 2 - 26 \)

   
   

   \( -6x = -24 \)

   
   

   \( x = \frac{-24}{-6} \)

   
   

   \( x = 4 \)

   
   


4. 
   

   \( 4x - 6 = 5x - 2(2x - 9) \)

   
   

   \( 4x - 6 = 5x - 4x + 18 \)

   
   

   \( 4x - 6 = x + 18 \)

   
   

   \( 4x - x = 18 + 6 \)

   
   

   \( 3x = 24 \)

   
   

   \( x = \frac{24}{3} \)

   
   

   \( x = 8 \)

   
   

Ответ: а) x = -4; б) x = -3/5; в) x = 4; г) x = 8.