8b^2-4b=10

Solution for 8b^2-4b=10 equation:

8b^2-4b=10

We move all terms to the left:

8b^2-4b-(10)=0

a = 8; b = -4; c = -10;
Δ = b2-4ac
Δ = -42-4·8·(-10)
Δ = 336
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{336}=\sqrt{16*21}=\sqrt{16}*\sqrt{21}=4\sqrt{21}$
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-4)-4\sqrt{21}}{2*8}=\frac{4-4\sqrt{21}}{16}
$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-4)+4\sqrt{21}}{2*8}=\frac{4+4\sqrt{21}}{16}
$