D=(y-5)(y-2)

Solution for D=(y-5)(y-2) equation:

=(D-5)(D-2)

We move all terms to the left:

-((D-5)(D-2))=0

We multiply parentheses ..

-((+D^2-2D-5D+10))=0


We calculate terms in parentheses: -((+D^2-2D-5D+10)), so:

(+D^2-2D-5D+10)

We get rid of parentheses

D^2-2D-5D+10

We add all the numbers together, and all the variables

D^2-7D+10

Back to the equation:

-(D^2-7D+10)


We get rid of parentheses

-D^2+7D-10=0

We add all the numbers together, and all the variables

-1D^2+7D-10=0

a = -1; b = 7; c = -10;
Δ = b2-4ac
Δ = 72-4·(-1)·(-10)
Δ = 9
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$D_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$D_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{9}=3$
$D_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(7)-3}{2*-1}=\frac{-10}{-2}
=+5
$
$D_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(7)+3}{2*-1}=\frac{-4}{-2}
=+2
$