Răspuns:
lg x / lg (x+2) = 1/2
C.E : x>0 x>0 x>0
x+2>0 <=> x>-2 <=> x>-2 => x∈ (0;∞)
lg(x+2) ≠ 0 x+2≠1 x≠ -1
<=> 2 lgx = lg(x+2)
<=> lg x² = lg(x+2)
=> x²=x+2 <=> x²-x-2=0 <=> (x+1)(x-2)=0
=> x=-1 sau x=2
Dar, x ∈ (0;∞)
deci S={2}
Sper că te-am ajutat !
