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One of the five quadratics below has a repeated root. (The other four have distinct roots.) What is the repeated root?
\(\begin{align*} &-x^2 + 18x + 81 \\ &3x^2 - 6x + 9 \\ &8x^2 - 32x + 32 \\ &25x^2 - 30x - 9 \\ &x^2 - 14x + 196 \end{align*}\)

 

It would be great if you could help me with this.

 

Thanks in advance! smiley

 Sep 1, 2022
 #1
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For equation \(ax^2 + bx + c = 0\)  to have repeated roots we must have \(b^2 - 4ac = 0\)

 

Calculate this for each quadratic in turn.

 Sep 1, 2022
 #2
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thanks

Guest Sep 1, 2022

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