For the following radical function- use this expression to find 2 y-values; use x-values such as 4- 5- 6- 7- . fractions and decimals would be fine…

For the following radical function, use this expression to find 2 y-values; use x-values such as 4, 5, 6, 7, … fractions and decimals would be fine too.Why can’t values less than 4 be used as replacements for x?