15b2+21b=0

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Solution for 15b2+21b=0 equation:



15b^2+21b=0
a = 15; b = 21; c = 0;
Δ = b2-4ac
Δ = 212-4·15·0
Δ = 441
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{441}=21$
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(21)-21}{2*15}=\frac{-42}{30} =-1+2/5 $
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(21)+21}{2*15}=\frac{0}{30} =0 $

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