3(x^2+4)=13x

Solution for 3(x^2+4)=13x equation:

3(x^2+4)=13x

We move all terms to the left:

3(x^2+4)-(13x)=0

We add all the numbers together, and all the variables

-13x+3(x^2+4)=0

We multiply parentheses

3x^2-13x+12=0

a = 3; b = -13; c = +12;
Δ = b2-4ac
Δ = -132-4·3·12
Δ = 25
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{25}=5$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-13)-5}{2*3}=\frac{8}{6}
=1+1/3
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-13)+5}{2*3}=\frac{18}{6}
=3
$