4y^2+9y+21=360

Solution for 4y^2+9y+21=360 equation:

4y^2+9y+21=360

We move all terms to the left:

4y^2+9y+21-(360)=0

We add all the numbers together, and all the variables

4y^2+9y-339=0

a = 4; b = 9; c = -339;
Δ = b2-4ac
Δ = 92-4·4·(-339)
Δ = 5505
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{-(9)-\sqrt{5505}}{2*4}=\frac{-9-\sqrt{5505}}{8}
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(9)+\sqrt{5505}}{2*4}=\frac{-9+\sqrt{5505}}{8}
$