Question 107446
{{{f(x)= sqrt(x - 4)}}}

We can find for what {{{x}}} is {{{ sqrt(x - 4) = 0}}}, and we will see that for f, it'll be {{{x >=4}}}, because any {{{x<4}}} will give us the square root of a negative number which is undefined.

 {{{f(x)}}} is defined for all real {{{x}}} excluding {{{4}}}, 
or from ({{{- infinity}}} to{{{4}}}] and from[{{{4}}} to {{{infinity}}}) 

to solve this, 
{{{sqrt(x - 4) = 0}}} raise both sides of an equation to a second power

{{{(sqrt(x - 4))^2 = 0^2}}}
{{{x - 4 = 0}}}
{{{x  =  4}}}

to sketch it, you will need at least two points because the graph will be a line (it is linear function):

{{{x }}} | {{{ f(x)}}}
{{{0 }}} | {{{ -4}}}
{{{4 }}} | {{{ 0}}}


here is the graph:

*[invoke graphing_linear_equations "slope-intercept", 1, 2, 3, 1, -4]