(5-d)(5-2d)=0

Solution for (5-d)(5-2d)=0 equation:

(5-d)(5-2d)=0

We add all the numbers together, and all the variables

(-1d+5)(-2d+5)=0

We multiply parentheses ..

(+2d^2-5d-10d+25)=0

We get rid of parentheses

2d^2-5d-10d+25=0

We add all the numbers together, and all the variables

2d^2-15d+25=0

a = 2; b = -15; c = +25;
Δ = b2-4ac
Δ = -152-4·2·25
Δ = 25
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{25}=5$
$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-15)-5}{2*2}=\frac{10}{4}
=2+1/2
$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-15)+5}{2*2}=\frac{20}{4}
=5
$