a) 2x + 14 = 3x + 12 14-12 = 3x - 2x x = 2
b) x(x+1) = 12 12 = 3·4 x= 3 x + 1 = 4 3·4 = 12
c) a/5 + 1/(b+1) = ? ptr. a/5 = 1/(b+1) ⇒ a·(b+1) = 5 5= 1·5 ⇒ a = 1 (b+1) = 5 b = 4 sau a= 5 b+ 1 = 1 b = 0
d) 2^(n+1) /3² = 2³ /3^n n+1 = 3 n = 2
e) (5/13)^n = (7/11)^n deoarece 5/13 ≠ 7/11⇒ n = 0 (5/13)^0 = 1 (7/11)^0 = 1