(j+9)(8j+7)=0

Solution for (j+9)(8j+7)=0 equation:

(j+9)(8j+7)=0

We multiply parentheses ..

(+8j^2+7j+72j+63)=0

We get rid of parentheses

8j^2+7j+72j+63=0

We add all the numbers together, and all the variables

8j^2+79j+63=0

a = 8; b = 79; c = +63;
Δ = b2-4ac
Δ = 792-4·8·63
Δ = 4225
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$j_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$j_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{4225}=65$
$j_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(79)-65}{2*8}=\frac{-144}{16}
=-9
$
$j_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(79)+65}{2*8}=\frac{-14}{16}
=-7/8
$