9=-2(a+4)9a

Solution for 9=-2(a+4)9a equation:

9=-2(a+4)9a

We move all terms to the left:

9-(-2(a+4)9a)=0


We calculate terms in parentheses: -(-2(a+4)9a), so:

-2(a+4)9a

We multiply parentheses

-18a^2-72a

Back to the equation:

-(-18a^2-72a)


We get rid of parentheses

18a^2+72a+9=0

a = 18; b = 72; c = +9;
Δ = b2-4ac
Δ = 722-4·18·9
Δ = 4536
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{4536}=\sqrt{324*14}=\sqrt{324}*\sqrt{14}=18\sqrt{14}$
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(72)-18\sqrt{14}}{2*18}=\frac{-72-18\sqrt{14}}{36}
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(72)+18\sqrt{14}}{2*18}=\frac{-72+18\sqrt{14}}{36}
$