3. Решите уравнение: a) 2²-x²= 0; б) 9y²-25 = 0; в) (2-x)²-x(x+1,5)=4.

3. Решим уравнения:

1. \( 2^2 - x^2 = 0 \)
   \( 4 - x^2 = 0 \)
   \( x^2 = 4 \)
   \( x = ± 2 \)
2. \( 9y^2 - 25 = 0 \)
   \( 9y^2 = 25 \)
   \( y^2 = \frac{25}{9} \)
   \( y = ± \sqrt{\frac{25}{9}} = ± \frac{5}{3} \)
3. \( (2-x)^2 - x(x+1.5) = 4 \)
   \( 4 - 4x + x^2 - x^2 - 1.5x = 4 \)
   \( 4 - 5.5x = 4 \)
   \( -5.5x = 0 \)
   \( x = 0 \)