1 5 2 3 1 2 LOG LOG X 1 X LOG LOG X 1 X (1)3 5ĐK
2)
1
5
2
3
1
2
log log
x
1
x
log log
x
1
x
(1)
3
5
Đk:
x0;
1 log log 1 log log 1 0x x x x 2
2
3
1
3
5
5
x x x x x xlog log 1 .log 1 0 log 1 1 2
2
2
2
3
1
5
5
2
0 log5
x 1 x 1*)
0 log5
x2
1 x
x 0*)
log5
x2
1 x
1 x2
1 x 5 x2
1 5 x ... x 125 Vậy BPT cú nghiệm
0;12x 5 Đề 87.