(3x)(7x=40)

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Solution for (3x)(7x=40) equation:



(3x)(7x=40)
We move all terms to the left:
(3x)(7x-(40))=0
We multiply parentheses
21x^2-120x=0
a = 21; b = -120; c = 0;
Δ = b2-4ac
Δ = -1202-4·21·0
Δ = 14400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{14400}=120$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-120)-120}{2*21}=\frac{0}{42} =0 $
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-120)+120}{2*21}=\frac{240}{42} =5+5/7 $

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