x2-16x-25=0

Solution for x2-16x-25=0 equation:

x2-16x-25=0

We add all the numbers together, and all the variables

x^2-16x-25=0

a = 1; b = -16; c = -25;
Δ = b2-4ac
Δ = -162-4·1·(-25)
Δ = 356
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{356}=\sqrt{4*89}=\sqrt{4}*\sqrt{89}=2\sqrt{89}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-16)-2\sqrt{89}}{2*1}=\frac{16-2\sqrt{89}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-16)+2\sqrt{89}}{2*1}=\frac{16+2\sqrt{89}}{2}
$