3x(x-7)=-30

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Solution for 3x(x-7)=-30 equation:



3x(x-7)=-30
We move all terms to the left:
3x(x-7)-(-30)=0
We add all the numbers together, and all the variables
3x(x-7)+30=0
We multiply parentheses
3x^2-21x+30=0
a = 3; b = -21; c = +30;
Δ = b2-4ac
Δ = -212-4·3·30
Δ = 81
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{81}=9$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-21)-9}{2*3}=\frac{12}{6} =2 $
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-21)+9}{2*3}=\frac{30}{6} =5 $

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