4y2-9y=28

Solution for 4y2-9y=28 equation:

4y^2-9y=28

We move all terms to the left:

4y^2-9y-(28)=0

a = 4; b = -9; c = -28;
Δ = b2-4ac
Δ = -92-4·4·(-28)
Δ = 529
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{529}=23$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-9)-23}{2*4}=\frac{-14}{8}
=-1+3/4
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-9)+23}{2*4}=\frac{32}{8}
=4
$