-r^2=6r-2=7

Solution for -r^2=6r-2=7 equation:

-r^2=6r-2=7

We move all terms to the left:

-r^2-(6r-2)=0

We add all the numbers together, and all the variables

-1r^2-(6r-2)=0

We get rid of parentheses

-1r^2-6r+2=0

a = -1; b = -6; c = +2;
Δ = b2-4ac
Δ = -62-4·(-1)·2
Δ = 44
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{44}=\sqrt{4*11}=\sqrt{4}*\sqrt{11}=2\sqrt{11}$
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-6)-2\sqrt{11}}{2*-1}=\frac{6-2\sqrt{11}}{-2}
$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-6)+2\sqrt{11}}{2*-1}=\frac{6+2\sqrt{11}}{-2}
$