The discriminant is denoted by the Greek letter delta in capital letters,
and is a number that is calculated with the coefficients of the equation:
[tex]\Delta=b^2-4ac[/tex]then we have the equation:
[tex]x^2-6x+9=0[/tex]where a = 1 , b = - 6 and c = 9
[tex]\begin{gathered} \Delta=(-6)^2-4(1)(9) \\ \Delta=36-36 \\ \Delta=0 \end{gathered}[/tex]Then:
if Δ is null (Δ = 0) the equation has only one solution (also, we can say that it has two equal solutions).