20-5y(y=+2)

Solution for 20-5y(y=+2) equation:

20-5y(y=+2)

We move all terms to the left:

20-5y(y-(+2))=0

We add all the numbers together, and all the variables

-5y(y-2)+20=0

We multiply parentheses

-5y^2+10y+20=0

a = -5; b = 10; c = +20;
Δ = b2-4ac
Δ = 102-4·(-5)·20
Δ = 500
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{500}=\sqrt{100*5}=\sqrt{100}*\sqrt{5}=10\sqrt{5}$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(10)-10\sqrt{5}}{2*-5}=\frac{-10-10\sqrt{5}}{-10}
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(10)+10\sqrt{5}}{2*-5}=\frac{-10+10\sqrt{5}}{-10}
$