A=x^2+9x+14

Solution for A=x^2+9x+14 equation:

=A^2+9A+14

We move all terms to the left:

-(A^2+9A+14)=0

We get rid of parentheses

-A^2-9A-14=0

We add all the numbers together, and all the variables

-1A^2-9A-14=0

a = -1; b = -9; c = -14;
Δ = b2-4ac
Δ = -92-4·(-1)·(-14)
Δ = 25
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$A_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$A_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{25}=5$
$A_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-9)-5}{2*-1}=\frac{4}{-2}
=-2
$
$A_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-9)+5}{2*-1}=\frac{14}{-2}
=-7
$