One of the five quadratics below has a repeated root. (The other four have distinct roots.) What is the repeated root?
x^2 - 2x + 1
x^2 - 4x - 4
x^2 + 6x - 9
x^2 + 26x + 25
x^2 - 5x + 4
The first one
We can tell if it has a repeated root if the discriminant = 0
So
(-2)^2 -4(1) (1) =
4 - 4 =
0
+866 
