Question

Dados A=log10x,B=log10 (x+2) e C=log10 3 calcule x para que A+B=C

Answer 1

log10x + log10 (x+2)=log10 3
= log 10 [x(x+2)] = log 10 3
= log 10 (x²+2x) = log10 3

x²+2x=3
x²+2x-3=0

Δ= $2^{2} - 4 (1)(-3)$
Δ= 16

x' = 1
x'' = -3