Question

determinar o valor de A,para A=logaritmo 30 + logaritmo 7 - logaritmo 21

Answer 1

Assumindo base 10 nos logs:
log 30 + log 7 - log 21 =
log 3.10 + log 7 - log 3.7=
log 3 + log 10 + log 7 - (log 3 + log 7) =
log 3 + log 10 + log 7 - log 3 - log 7 =
log 10 = 1.

Answer 2

$\log30+\log7-\log21=\log(\frac{30\cdot7}{21})=\log(\frac{210}{21})=\log10=1$