x=1/2x+1/3x+1/6x+1/7 amplifici fiecare termen x cu 42 1/2x cu 21 1/3x cu 14 1/6x cu 7 1/7 cu 6 42x=21x+14x+7x+6 42x=42x+6 42x-42x=6 0=6 x apartine multimei vide
x=1/2x+1/3x+1/6x+1/7x x=1/x(1/2+1/3+1/6+1/7) x^2=1/2+1/3+1/6+1/7 numitorul comun 42 x^2=(21+14+7+6)/42 x^2=48/42 x^2=8/7 x1,2=+-√8/√7 x1,2=+-2√2/√7 x1,2=+-2√14/7 daca x nu e la numitor x=x(1/2+1/3+1/6+1/7) ceea ce conduce la 42x=48x x=0
