3. Решите уравнение: a) 4x² + 9x = 0 б) -5x² - 25x = 0 в) -6x² + 18x = 0 г) -9x² - 27x = 0 д) 30x² - 6x = 0 e) -44x² - 22x = 0 ж) 8x² - 20x = 0 з) -52x² + 26x = 0

Решение:

1. a) 4x² + 9x = 0
   \( x(4x + 9) = 0 \)
   \( x = 0 \) или \( 4x + 9 = 0 \) \( \Rightarrow x = -9/4 \)
2. б) -5x² - 25x = 0
   \( -5x(x + 5) = 0 \)
   \( x = 0 \) или \( x + 5 = 0 \) \( \Rightarrow x = -5 \)
3. в) -6x² + 18x = 0
   \( -6x(x - 3) = 0 \)
   \( x = 0 \) или \( x - 3 = 0 \) \( \Rightarrow x = 3 \)
4. г) -9x² - 27x = 0
   \( -9x(x + 3) = 0 \)
   \( x = 0 \) или \( x + 3 = 0 \) \( \Rightarrow x = -3 \)
5. д) 30x² - 6x = 0
   \( 6x(5x - 1) = 0 \)
   \( x = 0 \) или \( 5x - 1 = 0 \) \( \Rightarrow x = 1/5 \)
6. е) -44x² - 22x = 0
   \( -22x(2x + 1) = 0 \)
   \( x = 0 \) или \( 2x + 1 = 0 \) \( \Rightarrow x = -1/2 \)
7. ж) 8x² - 20x = 0
   \( 4x(2x - 5) = 0 \)
   \( x = 0 \) или \( 2x - 5 = 0 \) \( \Rightarrow x = 5/2 \)
8. з) -52x² + 26x = 0
   \( -26x(2x - 1) = 0 \)
   \( x = 0 \) или \( 2x - 1 = 0 \) \( \Rightarrow x = 1/2 \)

Ответ: а) 0; -9/4; б) 0; -5; в) 0; 3; г) 0; -3; д) 0; 1/5; е) 0; -1/2; ж) 0; 5/2; з) 0; 1/2.