Diketahui log 2 = 0,3010; log 3 = 0,4771 dan log 7=0,8451 tentukan : A. Log 18 B. Log 21 C. Log 10,5 D. Log 1/7

KELAS/PELAJARAN : X/MATEMATIKA
MATERI : LOGARITMA
PENYELESAIAN :
A) log 18
[tex] = log( {3}^{2} \times 2) \\ = log {3}^{2} + log2 \\ = 2log3 + 0.3010[/tex]
= 2(0,4771) + 0,3010
= 0,9542 + 0,3010 = 1,2552
B) log 21 = log (3 x 7)
= log 3 + log 7
= 0,4771 + 0,8451 = 1,3222
C) log 10,5
[tex] = log( \frac{3 \times 7}{2} ) \\ = log3 + log7 - log2 [/tex]
= 0,4771 + 0,8451 - 0,3010 = 1,0212
D) log 1/7 = log 1 - log 7
= 0 - 0,8451
= - 0,8451