3(y+70)(y-40)=0

Solution for 3(y+70)(y-40)=0 equation:

3(y+70)(y-40)=0

We multiply parentheses ..

3(+y^2-40y+70y-2800)=0

We multiply parentheses

3y^2-120y+210y-8400=0

We add all the numbers together, and all the variables

3y^2+90y-8400=0

a = 3; b = 90; c = -8400;
Δ = b2-4ac
Δ = 902-4·3·(-8400)
Δ = 108900
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{108900}=330$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(90)-330}{2*3}=\frac{-420}{6}
=-70
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(90)+330}{2*3}=\frac{240}{6}
=40
$