-(10.5x)*2-(1.5x-6)x=0

Solution for -(10.5x)*2-(1.5x-6)x=0 equation:

-(10.5x)*2-(1.5x-6)x=0

We add all the numbers together, and all the variables

-(+10.5x)*2-(1.5x-6)x=0

We multiply parentheses

-x^2-20x+6x=0

We add all the numbers together, and all the variables

-1x^2-14x=0

a = -1; b = -14; c = 0;
Δ = b2-4ac
Δ = -142-4·(-1)·0
Δ = 196
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{196}=14$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-14)-14}{2*-1}=\frac{0}{-2}
=0
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-14)+14}{2*-1}=\frac{28}{-2}
=-14
$