15x2+21x+-72=0

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Solution for 15x2+21x+-72=0 equation:



15x^2+21x+-72=0
We add all the numbers together, and all the variables
15x^2+21x=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:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

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

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