(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

(z+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
$