The input x = 5 leads to the two outputs f(x) = 2 and f(x) = 1 (as shown by the green arrows in the attached image). In order to have a function, all of the inputs must lead to exactly one output.
Its False...because functions can put in more than one real numbers but the output can only have 1 possible number and in this the number 5 input has 2 outputs!!
