f(x)=0 x^2-8x+12=0 Coeficientii sunt a=1,b=(-8),c=12, Δ=b^2-4ac=(-8)^2-4*1*12=64-4*12=64-48=16>0, iar √Δ=4. Deci ecuatia are solutiile reale x1,2=[(-b)±√Δ]/(2a)=[-(-8)±4]/(2*1)=(8±4)/2. x1=(8-4)/2=4/2=2 x2=(8+4)/2=12/2=6 Multimea de solutii este S={2,6}.