Oblicz
Jess: log3 (3x−8) =2−x
24 lis 21:12
log:
x=2
24 lis 21:14
Blee:
log
3(3
x − 8) = 2−x ⇔ 3
x − 8 = 3
2−x
niech t = 3
x, t > 0
| | 9 | |
t − 8 = |
| ⇔ t2 − 8t − 9 = 0 ⇔ (t−9)(t+1) = 0 ⇔ t = 9 ⇔ 3x = 9 ⇔ x = 2 |
| | t | |
sprawdzenie:
log
3(9−8) = log
31 = 0 = 2−2
24 lis 21:14