2n2-n-21=0

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Solution for 2n2-n-21=0 equation:



2n^2-n-21=0
We add all the numbers together, and all the variables
2n^2-1n-21=0
a = 2; b = -1; c = -21;
Δ = b2-4ac
Δ = -12-4·2·(-21)
Δ = 169
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{169}=13$
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-1)-13}{2*2}=\frac{-12}{4} =-3 $
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-1)+13}{2*2}=\frac{14}{4} =3+1/2 $

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