X(42-x/3)=0

Solution for X(42-x/3)=0 equation:

X(42-X/3)=0

We add all the numbers together, and all the variables

X(-X/3+42)=0

We multiply parentheses

-1X^2+42X=0

a = -1; b = 42; c = 0;
Δ = b2-4ac
Δ = 422-4·(-1)·0
Δ = 1764
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1764}=42$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(42)-42}{2*-1}=\frac{-84}{-2}
=+42
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(42)+42}{2*-1}=\frac{0}{-2}
=0
$