(2-z)(2z+7)=0

Solution for (2-z)(2z+7)=0 equation:

(2-z)(2z+7)=0

We add all the numbers together, and all the variables

(-1z+2)(2z+7)=0

We multiply parentheses ..

(-2z^2-7z+4z+14)=0

We get rid of parentheses

-2z^2-7z+4z+14=0

We add all the numbers together, and all the variables

-2z^2-3z+14=0

a = -2; b = -3; c = +14;
Δ = b2-4ac
Δ = -32-4·(-2)·14
Δ = 121
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$z_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$z_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{121}=11$
$z_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-3)-11}{2*-2}=\frac{-8}{-4}
=+2
$
$z_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-3)+11}{2*-2}=\frac{14}{-4}
=-3+1/2
$