21x^2-39x+18=0

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Solution for 21x^2-39x+18=0 equation:



21x^2-39x+18=0
a = 21; b = -39; c = +18;
Δ = b2-4ac
Δ = -392-4·21·18
Δ = 9
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{9}=3$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-39)-3}{2*21}=\frac{36}{42} =6/7 $
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-39)+3}{2*21}=\frac{42}{42} =1 $

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