0=16x^2+21x-16

Solution for 0=16x^2+21x-16 equation:

0=16x^2+21x-16

We move all terms to the left:

0-(16x^2+21x-16)=0

We add all the numbers together, and all the variables

-(16x^2+21x-16)=0

We get rid of parentheses

-16x^2-21x+16=0

a = -16; b = -21; c = +16;
Δ = b2-4ac
Δ = -212-4·(-16)·16
Δ = 1465
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-21)-\sqrt{1465}}{2*-16}=\frac{21-\sqrt{1465}}{-32}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-21)+\sqrt{1465}}{2*-16}=\frac{21+\sqrt{1465}}{-32}
$