(2z-1)(9+z)=0

Solution for (2z-1)(9+z)=0 equation:

(2z-1)(9+z)=0

We add all the numbers together, and all the variables

(2z-1)(z+9)=0

We multiply parentheses ..

(+2z^2+18z-1z-9)=0

We get rid of parentheses

2z^2+18z-1z-9=0

We add all the numbers together, and all the variables

2z^2+17z-9=0

a = 2; b = 17; c = -9;
Δ = b2-4ac
Δ = 172-4·2·(-9)
Δ = 361
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$z_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$z_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{361}=19$
$z_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(17)-19}{2*2}=\frac{-36}{4}
=-9
$
$z_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(17)+19}{2*2}=\frac{2}{4}
=1/2
$