(2-z)(5z+6)=0

Solution for (2-z)(5z+6)=0 equation:

(2-z)(5z+6)=0

We add all the numbers together, and all the variables

(-1z+2)(5z+6)=0

We multiply parentheses ..

(-5z^2-6z+10z+12)=0

We get rid of parentheses

-5z^2-6z+10z+12=0

We add all the numbers together, and all the variables

-5z^2+4z+12=0

a = -5; b = 4; c = +12;
Δ = b2-4ac
Δ = 42-4·(-5)·12
Δ = 256
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$z_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$z_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{256}=16$
$z_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(4)-16}{2*-5}=\frac{-20}{-10}
=+2
$
$z_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(4)+16}{2*-5}=\frac{12}{-10}
=-1+1/5
$