Răspuns :
9a^2-4b^2=12
(3a)^2-(2b)^2= (3a+2b)•(3a-2b)=12
3a-2b=2 --> 3a+2b= 12÷2=6
(3a)^2-(2b)^2= (3a+2b)•(3a-2b)=12
3a-2b=2 --> 3a+2b= 12÷2=6
..
( 3a — 2b ) • ( 3a + 2b ) = 12
2 • ( 3a + 2b ) = 12
⇔ 3a + 2b = 12 : 2 ⇔
⇔ 3a + 2b = 6
..
( 3a — 2b ) • ( 3a + 2b ) = 12
2 • ( 3a + 2b ) = 12
⇔ 3a + 2b = 12 : 2 ⇔
⇔ 3a + 2b = 6
..