.25x(x-13)=7

Solution for .25x(x-13)=7 equation:

.25x(x-13)=7

We move all terms to the left:

.25x(x-13)-(7)=0

We multiply parentheses

x^2-13x-7=0

a = 1; b = -13; c = -7;
Δ = b2-4ac
Δ = -132-4·1·(-7)
Δ = 197
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{-(-13)-\sqrt{197}}{2*1}=\frac{13-\sqrt{197}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-13)+\sqrt{197}}{2*1}=\frac{13+\sqrt{197}}{2}
$