30=(4+2a)a

Solution for 30=(4+2a)a equation:

30=(4+2a)a

We move all terms to the left:

30-((4+2a)a)=0

We add all the numbers together, and all the variables

-((2a+4)a)+30=0


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

(2a+4)a

We multiply parentheses

2a^2+4a

Back to the equation:

-(2a^2+4a)


We get rid of parentheses

-2a^2-4a+30=0

a = -2; b = -4; c = +30;
Δ = b2-4ac
Δ = -42-4·(-2)·30
Δ = 256
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{256}=16$
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-4)-16}{2*-2}=\frac{-12}{-4}
=+3
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-4)+16}{2*-2}=\frac{20}{-4}
=-5
$