0=-x^2+7x+12

Solution for 0=-x^2+7x+12 equation:

0=-x^2+7x+12

We move all terms to the left:

0-(-x^2+7x+12)=0

We add all the numbers together, and all the variables

-(-x^2+7x+12)=0

We get rid of parentheses

x^2-7x-12=0

a = 1; b = -7; c = -12;
Δ = b2-4ac
Δ = -72-4·1·(-12)
Δ = 97
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{-(-7)-\sqrt{97}}{2*1}=\frac{7-\sqrt{97}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-7)+\sqrt{97}}{2*1}=\frac{7+\sqrt{97}}{2}
$