Y=-0,5x^2+2,5x

Solution for Y=-0,5x^2+2,5x equation:

=-0.5Y^2+2.5Y

We move all terms to the left:

-(-0.5Y^2+2.5Y)=0

We get rid of parentheses

0.5Y^2-2.5Y=0

a = 0.5; b = -2.5; c = 0;
Δ = b2-4ac
Δ = -2.52-4·0.5·0
Δ = 6.25
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{-(-2.5)-\sqrt{6.25}}{2*0.5}=\frac{2.5-\sqrt{6.25}}{1}
$
$Y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-2.5)+\sqrt{6.25}}{2*0.5}=\frac{2.5+\sqrt{6.25}}{1}
$