(y-4)(y-2.3)=0

Solution for (y-4)(y-2.3)=0 equation:

(y-4)(y-2.3)=0

We multiply parentheses ..

(+y^2-2.3y-4y+9.2)=0

We get rid of parentheses

y^2-2.3y-4y+9.2=0

We add all the numbers together, and all the variables

y^2-6.3y+9.2=0

a = 1; b = -6.3; c = +9.2;
Δ = b2-4ac
Δ = -6.32-4·1·9.2
Δ = 2.89
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-6.3)-\sqrt{2.89}}{2*1}=\frac{6.3-\sqrt{2.89}}{2}
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-6.3)+\sqrt{2.89}}{2*1}=\frac{6.3+\sqrt{2.89}}{2}
$