fie x1 si x2 radacinile ecuatiei x2+px+q=0.Sa se formeze ecuatii de gradul al doilea in y,ale caror radacini sunt:
b)y1=x1+ 1/x2; y2=x2 + 1/x1
c) y1=(x1+x2)^2
y2=(x1-x2)^2