(2a-1)(2a+1)=a

Solution for (2a-1)(2a+1)=a equation:

(2a-1)(2a+1)=a

We move all terms to the left:

(2a-1)(2a+1)-(a)=0

We add all the numbers together, and all the variables

-1a+(2a-1)(2a+1)=0

We use the square of the difference formula

4a^2-1a-1=0

a = 4; b = -1; c = -1;
Δ = b2-4ac
Δ = -12-4·4·(-1)
Δ = 17
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{-(-1)-\sqrt{17}}{2*4}=\frac{1-\sqrt{17}}{8}
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-1)+\sqrt{17}}{2*4}=\frac{1+\sqrt{17}}{8}
$