11d*9d=5d*25

Solution for 11d*9d=5d*25 equation:

11d*9d=5d*25

We move all terms to the left:

11d*9d-(5d*25)=0

We add all the numbers together, and all the variables

11d*9d-(+5d*25)=0

Wy multiply elements

99d^2-(+5d*25)=0

We get rid of parentheses

99d^2-5d*25=0

Wy multiply elements

99d^2-125d=0

a = 99; b = -125; c = 0;
Δ = b2-4ac
Δ = -1252-4·99·0
Δ = 15625
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{15625}=125$
$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-125)-125}{2*99}=\frac{0}{198}
=0
$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-125)+125}{2*99}=\frac{250}{198}
=1+26/99
$