a^2-3a-1=6

Solution for a^2-3a-1=6 equation:

a^2-3a-1=6

We move all terms to the left:

a^2-3a-1-(6)=0

We add all the numbers together, and all the variables

a^2-3a-7=0

a = 1; b = -3; c = -7;
Δ = b2-4ac
Δ = -32-4·1·(-7)
Δ = 37
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-3)-\sqrt{37}}{2*1}=\frac{3-\sqrt{37}}{2}
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-3)+\sqrt{37}}{2*1}=\frac{3+\sqrt{37}}{2}
$