X(x-9)=630

Solution for X(x-9)=630 equation:

X(X-9)=630

We move all terms to the left:

X(X-9)-(630)=0

We multiply parentheses

X^2-9X-630=0

a = 1; b = -9; c = -630;
Δ = b2-4ac
Δ = -92-4·1·(-630)
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*1}=\frac{-42}{2}
=-21
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-9)+51}{2*1}=\frac{60}{2}
=30
$