จารีรัตน์502 เพิ่มเติม

[jareerat502]

1. log 2x = 3
2x = 103
2x = 1,000
X = 1,000/2
ตอบ = 500

2. log(3x+5) = 2
3x+5 = 102
ตอบ 3x+5 =100

3. log2x = log 2+5
log2x = log 2+5 log 10
log 2x = log 2+ log 105
log 2x = log(2×105)
2x = 2×105
X = 2×105/2
X = 105
X = 100,000
3x = 100-5
ตอบ X = 95/3


4. 2x = 32
2 x = 25
ตอบ x = 5

5. 9x = 32x
32x = 32x
2x = 2x
ตอบ x€ R

6. log 2.56 = 0.4082
log N = 0.4082
log N = log 2.56
N = 2.56 ตอบ

7. log N = 3.4082
= 3+0.4082
= 3 log 10+log 2.56
= log 103 + log 2.56
Log N = log(103×2.56
N = 103×2.56
N = 2,560



8. log 0.00371 = log(3.71×-3) = log 3.71+log10-3
= log 3.71+(-3) log 10 = log 3.71-3
= 0.5694-3 = 2.4036 ตอบ


9. log 832 = log(8.32×102) = log 8.32+log 102
= log 8.32+2 log 10 = log 10 = log 8.32+2
= 0.9201+2 = 2.9201 ตอบ

10. log 0.832 = log(8.32×10-1 = log 8.32+log 10-1
= log 8.32+(-1) log 10 = log 8.32-1
= 0.9201-0 = -0.0799 ตอบ

11. log 37,00 = log(3071×4) = log 3.71+log 104
= log 3.71+4 log 10 = log 3.71+4
= 4+log 3.71 = 4+0.5694 4 4.5694 ตอบ

12. 9 = 32 13. 10,000 = 104 14. 7 = (49)1/2
ตอบ log = 2 ตอบ log10 10,000 = 4 ตอบ log49 = ½

15. ½ = log4 2 16. 3 = log4 125 17. log5 5√5 = 3
Log4 2 = ½ log5 125 = 3 √53 = 5√5
ตอบ 41/2 = 2 ตอบ 53 = 125 ตอบ (√5)3 = 5√5

18. log2x = 5
x = 25
ตอบ x = 32

19. log10 x = 2
X = 102
ตอบ X = 100

20. logx 1000 = 3
a. = x3
X = 3√1,000
ตอบ = 10

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