16z^2-16z-21=0

Solution for 16z^2-16z-21=0 equation:

16z^2-16z-21=0

a = 16; b = -16; c = -21;
Δ = b2-4ac
Δ = -162-4·16·(-21)
Δ = 1600
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$z_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$z_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1600}=40$
$z_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-16)-40}{2*16}=\frac{-24}{32}
=-3/4
$
$z_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-16)+40}{2*16}=\frac{56}{32}
=1+3/4
$