Answer:
The boundary equation is  400  ≤  x ≤  700 .
Step-by-step explanation:
Let x represents the wavelength in nanometers.
Maximum wavelength to have visible lights: 700 nanometers
Minimum wavelengths to have visible lights: 400 nanometers
The inequalities for these two boundary conditions would be: Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â
                400  ≤  x ≤  700 nanometers       Â
The absolute value equation would be:
                  |x -400| > 0
                  |x -700| > 0