Question

rezolvati in multimea numerelor reale ecuatia logx din (x+2)=2

Answer 1

log x (x+2)=2 c.e. {x>0=> x€(0,+∞)        {x≠1        {x+2>0=>x>–2=>x€(–2,+∞) => D=(0,+∞)\{1}  x²=x+2=>x²–x–2=0 a=1; b=–1, c=–2 ∆=b²–4ac=(–1)²–4·1·(–2)=1+8=9  x1,2=(–b±√∆)/2a=(1±√9)/2=(1±3)/2 x1=(1+3)/2=4/2=2€D x2=(1–3)/2=–2/2=–1 €/ D (adică nu aparține lui D)  S={2}