Question 574248
You have a typo in your expression.  I'm going to assume it's a quadratic:
    solve x in 6(x^2+1)=13x
.
To solve any quadratic, set one side to zero:
6(x^2+1)=13x
6x^2+6=13x
6x^2-13x+6=0
6x^2-9x-4x+6=0
group:
(6x^2-9x)-(4x-6)=0
3x(2x-3)-2(2x-3)=0
(2x-3)(3x-2) = 0
x = {3/2, 2/3}