Diketahui log 2 = 0,3010 ; log 3 = 0,4771 ; dan log 7 = 0,8451 tentukan: beri contoh!

Contoh :
a). log 18
b). log 21
c). log 10,5
d). log 1/7

Jawab

a) log 18 = log(3² x 2) 
= log 3² + log 2 
= 2 * log 3 + log 2 = 2(0,4771) + (0,3010) 
= 1.2552 

b. log 21 = log(7 x 3) 
= log 7 + log 3 = 0,8451 + 0,4771 
= 1.3222 

c. log 10,5 = log(105/10) 
= log(3 x 5 x 7) / 10) 
= log 3 + log 5 + log 7 – log 10 
= 0,3010 + 0,4771 + 0,8451 – 1 
= 0.6232 

d. log (1/7) = log 7⁻¹ = -log 7 
= -0,8451

Contoh :
tentukan :
a) log 6
b) log 14
c) log 1,5
jawab :
a) log 6 = log 2 + log 3 = 0,3010 + 0,4771 = 0,7781
b) log 14 = log 2 + log 7 = 0,3010 + 0,8451 = 1,1461
c) log 1,5 = log (3/2) = log 3 – log 2 = 0,4771 – 0,3010 = 0,1761