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rezolvati in multimea numerelor reale ecuatia √x 2=x

Răspuns :

2√x=x ridicam la ² ecuatia ⇒ 2²(√2)²=x²
⇒4·2=x²⇒8=x²⇒x=2√2 presupun ca asa :-?
√(x+2)=x
(√(x+2))²=x²
x+2=x²
-x²+x+2=0      inmultim -1
x²-x-2=0
Δ=1+8=9
x1=(1-3)/2=-2/2=-1
x2=(1+3)/2=4/2=2
S={-1,2}