Răspuns :
Formulă :
[tex] {a}^{2} - {b}^{2} = (a - b)(a + b)[/tex]
[tex] {(2x + 1)}^{2} - 9 = {(2x + 1)}^{2} - {3}^{2} [/tex]
[tex]a = 2x + 1[/tex]
[tex]b = 3[/tex]
[tex] = (2x + 1 - 3)(2x + 1 + 3)[/tex]
[tex] = (2x - 2)(2x + 4)[/tex]
[tex] = 2(x - 1) \times 2(x + 2)[/tex]
[tex] = 2 \times 2(x - 1)(x + 2)[/tex]
[tex] = 4(x - 1)(x + 2)[/tex]
(2x + 1)² - 9 =
Folosim a² - b² = (a + b)(a - b)
= (2x + 1)² - 3²
= (2x + 1 + 3)(2x + 1 - 3)
= (2x + 4)(2x - 2)
= 2(x + 2)·2(x - 1)
= 4(x + 2)(x - 1)