3a(18+7a)=4a

Solution for 3a(18+7a)=4a equation:

3a(18+7a)=4a

We move all terms to the left:

3a(18+7a)-(4a)=0

We add all the numbers together, and all the variables

3a(7a+18)-4a=0

We add all the numbers together, and all the variables

-4a+3a(7a+18)=0

We multiply parentheses

21a^2-4a+54a=0

We add all the numbers together, and all the variables

21a^2+50a=0

a = 21; b = 50; c = 0;
Δ = b2-4ac
Δ = 502-4·21·0
Δ = 2500
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2500}=50$
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(50)-50}{2*21}=\frac{-100}{42}
=-2+8/21
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(50)+50}{2*21}=\frac{0}{42}
=0
$