0=-3x^2+42x

Solution for 0=-3x^2+42x equation:

0=-3x^2+42x

We move all terms to the left:

0-(-3x^2+42x)=0

We add all the numbers together, and all the variables

-(-3x^2+42x)=0

We get rid of parentheses

3x^2-42x=0

a = 3; b = -42; c = 0;
Δ = b2-4ac
Δ = -422-4·3·0
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*3}=\frac{0}{6}
=0
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-42)+42}{2*3}=\frac{84}{6}
=14
$