There is an entry error.  The radical should not contain the equals sign, hence anything to the right of the equals sign is treated as "=X+2" rather than "square root of X+2".  Shown below are two images, one in which the radical sign includes the equal symbol and in the second image both radicals are entered on either side of the equal sign. 

It is also worth noting that 'X' and 'x' are different variables, so always be aware that a variable is case-sensitive.