x2+16x=-15

Solution for x2+16x=-15 equation:

x2+16x=-15

We move all terms to the left:

x2+16x-(-15)=0

We add all the numbers together, and all the variables

x^2+16x+15=0

a = 1; b = 16; c = +15;
Δ = b2-4ac
Δ = 162-4·1·15
Δ = 196
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{196}=14$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(16)-14}{2*1}=\frac{-30}{2}
=-15
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(16)+14}{2*1}=\frac{-2}{2}
=-1
$