3x(x+5)=-15

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Solution for 3x(x+5)=-15 equation:



3x(x+5)=-15
We move all terms to the left:
3x(x+5)-(-15)=0
We add all the numbers together, and all the variables
3x(x+5)+15=0
We multiply parentheses
3x^2+15x+15=0
a = 3; b = 15; c = +15;
Δ = b2-4ac
Δ = 152-4·3·15
Δ = 45
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:
$\sqrt{\Delta}=\sqrt{45}=\sqrt{9*5}=\sqrt{9}*\sqrt{5}=3\sqrt{5}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(15)-3\sqrt{5}}{2*3}=\frac{-15-3\sqrt{5}}{6} $
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(15)+3\sqrt{5}}{2*3}=\frac{-15+3\sqrt{5}}{6} $

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