(x*3)*(x+3)=210

Solution for (x*3)*(x+3)=210 equation:

(x*3)(x+3)=210

We move all terms to the left:

(x*3)(x+3)-(210)=0

We add all the numbers together, and all the variables

(+x*3)(x+3)-210=0

We multiply parentheses ..

(+3x^2+9x)-210=0

We get rid of parentheses

3x^2+9x-210=0

a = 3; b = 9; c = -210;
Δ = b2-4ac
Δ = 92-4·3·(-210)
Δ = 2601
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2601}=51$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(9)-51}{2*3}=\frac{-60}{6}
=-10
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(9)+51}{2*3}=\frac{42}{6}
=7
$