Question 1061745
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On quadratic equations, on solving quadratic equations, on the quadratic formula see the lessons

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/quadratic/lessons/Introduction-Into-Quadratics.lesson>Introduction into Quadratic Equations</A>

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/quadratic/lessons/proof-of-quadratic-by-completing-the-square.lesson>PROOF of quadratic formula by completing the square</A>

in this site.


A quadratic equation with real coefficients can have two, one or NO real zeros.
It is the discriminant of a quadratic equation who determines how many real roots the equation has.


These issues are discussed in the referred lessons.


If you look for the roots of the quadratic equation over the complex numbers, then there are two roots.
Sometimes the two roots can merge into one.
Again, it is the discriminant of the equation who determines it.