Is the square root of -13 rational or irrational or not a real number

1.what effect does replacing x with x−4 have on the graph for the function f(x) ? f(x)=|x−6|+2 the graph is shifted 4 units up. the graph is shifted 4 units down. the graph is shifted 4 units left. the graph is shifted 4 units right. 2.what are the coordinates of the hole in the graph of the function f(x) ? f(x)=x^2+3x−28/x+7 3.which graph represents the function?