Can you identify real numbers as either rational or irrational?

No. The definition of an irrational number is a number which is not a rational number, namely it is not the ratio between two integers. If a real number is not rational, then by definition it is irrational.

2nd one in the first row is correct

first, you divide the triangle in two, tô form a retangle triangle. after, using pythagoream theorem:

18^2 = 14^2 + (x/2)^2

(x^2/4) + 196 = 324

x^2/4 = 324 - 196

x^2/4 = 128

x^2 = 512

x = √512

x = √2^9

x = 16√2 cm

i hope i you.