Indicate with true (T) or false (F) whether the following functions are polynomials.
$f(x) = x+2.$
$f(x) = \sqrt{2}.$
$f(x) = \sqrt{x}.$
$f(x) = |x|.$
$f(x) = \frac{1}{x}.$
$f(x) = (x+1)^{200000}.$
$f(x) = \sqrt{1+x^2}.$
Hint: You need to understand the definition of the word polynomial.