-5b+2b^2+5-7b^2=0

Solution for -5b+2b^2+5-7b^2=0 equation:

-5b+2b^2+5-7b^2=0

We add all the numbers together, and all the variables

-5b^2-5b+5=0

a = -5; b = -5; c = +5;
Δ = b2-4ac
Δ = -52-4·(-5)·5
Δ = 125
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:

$\sqrt{\Delta}=\sqrt{125}=\sqrt{25*5}=\sqrt{25}*\sqrt{5}=5\sqrt{5}$
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-5)-5\sqrt{5}}{2*-5}=\frac{5-5\sqrt{5}}{-10}
$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-5)+5\sqrt{5}}{2*-5}=\frac{5+5\sqrt{5}}{-10}
$