r2+18r+81=0

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Solution for r2+18r+81=0 equation: 



r2+18r+81=0

We add all the numbers together, and all the variables

r^2+18r+81=0

a = 1; b = 18; c = +81;
Δ = b2-4ac
Δ = 182-4·1·81
Δ = 0
Delta is equal to zero, so there is only one solution to the equation

                              Stosujemy wzór:
$r=\frac{-b}{2a}=\frac{-18}{2}=-9$

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