(9+1y)(5y+7)=0

Solution for (9+1y)(5y+7)=0 equation:

(9+1y)(5y+7)=0

We add all the numbers together, and all the variables

(y+9)(5y+7)=0

We multiply parentheses ..

(+5y^2+7y+45y+63)=0

We get rid of parentheses

5y^2+7y+45y+63=0

We add all the numbers together, and all the variables

5y^2+52y+63=0

a = 5; b = 52; c = +63;
Δ = b2-4ac
Δ = 522-4·5·63
Δ = 1444
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1444}=38$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(52)-38}{2*5}=\frac{-90}{10}
=-9
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(52)+38}{2*5}=\frac{-14}{10}
=-1+2/5
$