a) D=(-2)²-4•1•(-48)=4+192=196 , vD=14
x1=(2+14)/2=8
x2=(2-14)/2=-6
x²-2x-48 =(x-8)•(x+6)
b) D=12²-4*36*1=144-144=0
x=12/(2*36)=1/6
36x²-12x+1= 36(x-1/6)*(x-1/6)
