a^2-6a=-3

Solution for a^2-6a=-3 equation:

a^2-6a=-3

We move all terms to the left:

a^2-6a-(-3)=0

We add all the numbers together, and all the variables

a^2-6a+3=0

a = 1; b = -6; c = +3;
Δ = b2-4ac
Δ = -62-4·1·3
Δ = 24
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{24}=\sqrt{4*6}=\sqrt{4}*\sqrt{6}=2\sqrt{6}$
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-6)-2\sqrt{6}}{2*1}=\frac{6-2\sqrt{6}}{2}
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-6)+2\sqrt{6}}{2*1}=\frac{6+2\sqrt{6}}{2}
$