63=(x+21)3x

Solution for 63=(x+21)3x equation:

63=(x+21)3x

We move all terms to the left:

63-((x+21)3x)=0


We calculate terms in parentheses: -((x+21)3x), so:

(x+21)3x

We multiply parentheses

3x^2+63x

Back to the equation:

-(3x^2+63x)


We get rid of parentheses

-3x^2-63x+63=0

a = -3; b = -63; c = +63;
Δ = b2-4ac
Δ = -632-4·(-3)·63
Δ = 4725
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{4725}=\sqrt{225*21}=\sqrt{225}*\sqrt{21}=15\sqrt{21}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-63)-15\sqrt{21}}{2*-3}=\frac{63-15\sqrt{21}}{-6}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-63)+15\sqrt{21}}{2*-3}=\frac{63+15\sqrt{21}}{-6}
$