Answer:
[tex]n = - 4 \: or \: n = 8[/tex]
Step-by-step explanation:
If the point (2,n) lies on the circle whose equation is:
[tex]( {x - 4)}^{2}  +  {(y - 2)}^{2}  = 40[/tex]
Then this point must satisfy the equation of the circle:
We substitute x=2 and y=n into the equation to get:
[tex]( {2 - 4)}^{2}  +  {(n - 2)}^{2}  = 40[/tex]
We simplify:
[tex]4+  {(n - 2)}^{2}  = 40[/tex]
This implies that,
[tex]{(n - 2)}^{2}  = 40 - 4[/tex]
[tex] {(n - 2)}^{2}  =36[/tex]
Take square root;
[tex]n - 2 =  \pm \sqrt{36} [/tex]
Evaluate:
[tex]n - 2 =  \pm6[/tex]
[tex]n =2  \pm6[/tex]
[tex]n =2   - 6 \: or \: n = 2 + 6[/tex]
[tex]n = - 4 \: or \: n = 8[/tex]