(m+7)(8m-9)=0

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

(m+7)(8m-9)=0

We multiply parentheses ..

(+8m^2-9m+56m-63)=0

We get rid of parentheses

8m^2-9m+56m-63=0

We add all the numbers together, and all the variables

8m^2+47m-63=0

a = 8; b = 47; c = -63;
Δ = b2-4ac
Δ = 472-4·8·(-63)
Δ = 4225
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$m_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$m_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{4225}=65$
$m_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(47)-65}{2*8}=\frac{-112}{16}
=-7
$
$m_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(47)+65}{2*8}=\frac{18}{16}
=1+1/8
$