4a^2-20.5a+25=0

Solution for 4a^2-20.5a+25=0 equation:

4a^2-20.5a+25=0

a = 4; b = -20.5; c = +25;
Δ = b2-4ac
Δ = -20.52-4·4·25
Δ = 20.25
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{-(-20.5)-\sqrt{20.25}}{2*4}=\frac{20.5-\sqrt{20.25}}{8}
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-20.5)+\sqrt{20.25}}{2*4}=\frac{20.5+\sqrt{20.25}}{8}
$