Step-by-step explanation:
I assume you mean you want to find the roots. Simply set J(x) equal to 0 and solve for x.
0 = (x − 4)² − 2
2 = (x − 4)²
±√2 = x − 4
x = 4 ± √2
The roots are x = 4 − √2 and x = 4 + √2. J(x) can be written in factored form as:
J(x) = (x − (4 − √2)) (x − (4 + √2))
J(x) = (x − 4 + √2) (x − 4 − √2)