x(x+5)=6(6+15)

Solution for x(x+5)=6(6+15) equation:

x(x+5)=6(6+15)

We move all terms to the left:

x(x+5)-(6(6+15))=0

We add all the numbers together, and all the variables

x(x+5)-(621)=0

We add all the numbers together, and all the variables

x(x+5)-621=0

We multiply parentheses

x^2+5x-621=0

a = 1; b = 5; c = -621;
Δ = b2-4ac
Δ = 52-4·1·(-621)
Δ = 2509
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{-(5)-\sqrt{2509}}{2*1}=\frac{-5-\sqrt{2509}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(5)+\sqrt{2509}}{2*1}=\frac{-5+\sqrt{2509}}{2}
$