15x2+42x-9=0

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Solution for 15x2+42x-9=0 equation:



15x^2+42x-9=0
a = 15; b = 42; c = -9;
Δ = b2-4ac
Δ = 422-4·15·(-9)
Δ = 2304
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2304}=48$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(42)-48}{2*15}=\frac{-90}{30} =-3 $
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(42)+48}{2*15}=\frac{6}{30} =1/5 $

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