(10y-9)(3y+7)=0

Solution for (10y-9)(3y+7)=0 equation:

(10y-9)(3y+7)=0

We multiply parentheses ..

(+30y^2+70y-27y-63)=0

We get rid of parentheses

30y^2+70y-27y-63=0

We add all the numbers together, and all the variables

30y^2+43y-63=0

a = 30; b = 43; c = -63;
Δ = b2-4ac
Δ = 432-4·30·(-63)
Δ = 9409
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{9409}=97$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(43)-97}{2*30}=\frac{-140}{60}
=-2+1/3
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(43)+97}{2*30}=\frac{54}{60}
=9/10
$