Question 669245
I'll do the first one. You can use the same process to solve the other 2
Get the term with radical by itself
{{{sqrt(6)x  = x + 8}}}  note that I read your problem as {{{sqrt(6) *x }}} not {{{sqrt(6x)}}}. If the second one is what you want, then modify the following steps accordingly

now square both sides
{{{(sqrt(6)x)^2 = (x+8)^2}}}

simplify
{{{(sqrt(6))^2 * x^2 = x^2 + 18x + 64}}}
{{{6x^x = x^2 +16x +64}}}

{{{5x^2 - 16x - 64 = 0}}}

Solve using quadratic equation
*[invoke quadratic "x", 5, -16, -64 ]

then pick the solutions that 'make sense'