-x(6-2x)=7

Solution for -x(6-2x)=7 equation:

-x(6-2x)=7

We move all terms to the left:

-x(6-2x)-(7)=0

We add all the numbers together, and all the variables

-x(-2x+6)-7=0

We multiply parentheses

2x^2-6x-7=0

a = 2; b = -6; c = -7;
Δ = b2-4ac
Δ = -62-4·2·(-7)
Δ = 92
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{92}=\sqrt{4*23}=\sqrt{4}*\sqrt{23}=2\sqrt{23}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-6)-2\sqrt{23}}{2*2}=\frac{6-2\sqrt{23}}{4}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-6)+2\sqrt{23}}{2*2}=\frac{6+2\sqrt{23}}{4}
$