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

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

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

We add all the numbers together, and all the variables

(m-9)(-1m+7)=0

We multiply parentheses ..

(-1m^2+7m+9m-63)=0

We get rid of parentheses

-1m^2+7m+9m-63=0

We add all the numbers together, and all the variables

-1m^2+16m-63=0

a = -1; b = 16; c = -63;
Δ = b2-4ac
Δ = 162-4·(-1)·(-63)
Δ = 4
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$m_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$m_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{4}=2$
$m_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(16)-2}{2*-1}=\frac{-18}{-2}
=+9
$
$m_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(16)+2}{2*-1}=\frac{-14}{-2}
=+7
$