(14y+21)(1.8-0.3y)=0

Solution for (14y+21)(1.8-0.3y)=0 equation:

(14y+21)(1.8-0.3y)=0

We add all the numbers together, and all the variables

(14y+21)(-0.3y+1.8)=0

We multiply parentheses ..

(+0y^2+25.2y+0y+37.8)=0

We get rid of parentheses

0y^2+25.2y+0y+37.8=0

We add all the numbers together, and all the variables

y^2+26.2y+37.8=0

a = 1; b = 26.2; c = +37.8;
Δ = b2-4ac
Δ = 26.22-4·1·37.8
Δ = 535.24
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{-(26.2)-\sqrt{535.24}}{2*1}=\frac{-26.2-\sqrt{535.24}}{2}
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(26.2)+\sqrt{535.24}}{2*1}=\frac{-26.2+\sqrt{535.24}}{2}
$