Respuesta :

Answer:

Step-by-step explanation:

9 = 3 * 3 = 3²

4x² = 2²x² = (2x)²

9 - 4x² = 3² - (2x)²     {a² - b² = (a + b)(a - b) ; a = 3 ; b = 2x}

          = (3 +2x)(3 - 2x)