-x2=9x+16

Solution for -x2=9x+16 equation:

-x2=9x+16

We move all terms to the left:

-x2-(9x+16)=0

We add all the numbers together, and all the variables

-1x^2-(9x+16)=0

We get rid of parentheses

-1x^2-9x-16=0

a = -1; b = -9; c = -16;
Δ = b2-4ac
Δ = -92-4·(-1)·(-16)
Δ = 17
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{-(-9)-\sqrt{17}}{2*-1}=\frac{9-\sqrt{17}}{-2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-9)+\sqrt{17}}{2*-1}=\frac{9+\sqrt{17}}{-2}
$