One of the five quadratics below has a repeated root. (The other four have distinct roots.) What is the repeated root?
−x2+18x+813x2−6x+98x2−32x+3225x2−30x−9x2−14x+196
+2668 For a quadratic to have distinct roots, it's must be the form: a2x2±2abx+b2
For example, applying this to the fifth one yields: 12x2−2×1×14x+142, which equals: x2−28x+196, this, isn't true, so it isn't 5.
Can you do the rest?
Thank you for the help! It helps me learn a lot better when people don't give direct answers, but hints and help. Thank you!
+118703 That is really good to here. Thanks 
And thanks for your teaching style answer Builderboi.
If you become a member you will get known (positively I think) and then you will get a consistently good response (like this one) from answerers here. 
+2668 Guest: I'm so glad I could help!
Melody: Thank you!
Also, I just realized my original answer has a typo, it should be "For a quadratic to have repeated roots", not "For a quadratic to have distinct roots"
