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Rezolavati in Q ecuatia :X2 (la a 2a) = 8

Răspuns :

x²=8
x²-8=0
x²-(√8)²=0
(x-√8)(x+√8)=0
x1=√8∉Q
x2=-√8∉Q

In Q avem S=∅

in R avem S={-√8';√8}={-2√2;2√2}
S∈R\Q