281=3x(3+x)

Solution for 281=3x(3+x) equation:

281=3x(3+x)

We move all terms to the left:

281-(3x(3+x))=0

We add all the numbers together, and all the variables

-(3x(x+3))+281=0


We calculate terms in parentheses: -(3x(x+3)), so:

3x(x+3)

We multiply parentheses

3x^2+9x

Back to the equation:

-(3x^2+9x)


We get rid of parentheses

-3x^2-9x+281=0

a = -3; b = -9; c = +281;
Δ = b2-4ac
Δ = -92-4·(-3)·281
Δ = 3453
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-9)-\sqrt{3453}}{2*-3}=\frac{9-\sqrt{3453}}{-6}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-9)+\sqrt{3453}}{2*-3}=\frac{9+\sqrt{3453}}{-6}
$