100a^2=400a

Solution for 100a^2=400a equation:

100a^2=400a

We move all terms to the left:

100a^2-(400a)=0

a = 100; b = -400; c = 0;
Δ = b2-4ac
Δ = -4002-4·100·0
Δ = 160000
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{160000}=400$
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-400)-400}{2*100}=\frac{0}{200}
=0
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-400)+400}{2*100}=\frac{800}{200}
=4
$