Răspuns:
Explicație pas cu pas:
9a^2-4b^2=(3a-2b)(3a+2b)
12=2* (.......)
deci paranteza =6
Practic se aplica formula x^2-y^2=(x-y)(x+y)
9 a² - 4 b² = 12 si 3 a - 2 b = 2
9 a² - 4 b² = ( 3 a - 2 b ) ( 3 a + 2 b ) → aplic formula a² - b²= (a-b)(a+b)
( 3 a - 2 b ) ( 3 a + 2 b ) = 12
2 × ( 3 a + 2 b ) = 12
3 a + 2 b = 12 : 2
3 a + 2 b = 6
