(7y+18)(7y+15)=0

Solution for (7y+18)(7y+15)=0 equation:

(7y+18)(7y+15)=0

We multiply parentheses ..

(+49y^2+105y+126y+270)=0

We get rid of parentheses

49y^2+105y+126y+270=0

We add all the numbers together, and all the variables

49y^2+231y+270=0

a = 49; b = 231; c = +270;
Δ = b2-4ac
Δ = 2312-4·49·270
Δ = 441
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{441}=21$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(231)-21}{2*49}=\frac{-252}{98}
=-2+4/7
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(231)+21}{2*49}=\frac{-210}{98}
=-2+1/7
$