Y=-28x^2+7x

Solution for Y=-28x^2+7x equation:

=-28Y^2+7Y

We move all terms to the left:

-(-28Y^2+7Y)=0

We get rid of parentheses

28Y^2-7Y=0

a = 28; b = -7; c = 0;
Δ = b2-4ac
Δ = -72-4·28·0
Δ = 49
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$Y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$Y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{49}=7$
$Y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-7)-7}{2*28}=\frac{0}{56}
=0
$
$Y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-7)+7}{2*28}=\frac{14}{56}
=1/4
$