1) 3^x+2*3^x-1=1
3^(x +2 +x -1) = 3^0
3^(2x+1) = 3^0
2x +1 = 0
2x = -1
x = -1/2
2) ОДЗ-?
х-2> 0 x > 2
x² -3x ≠0, ⇒ x ≠0 и х ≠3
Ответ: х∈ (2;3)∪(3; +∞)
3)
→ → → → →
а(2; -1; 3) и b(4; 2; 0) m = 2a -1/2b
→ → → → →
2a(4; -2; 6), -1/2 b (-2; -1; 0), m = 2a -1/2b (2; -3; 6)
|m| = √(2² +(-3)² +6²) = √(4 +9 +36) = √49 = 7