If an inequality is strictly less than or strictly greater than a number the circle is open on a number line?

Look at arnold's attempt to solve the equation for b: 3b = 12 b = 3 · 12 b = 36 describe the mistake that arnold made.

Aword processing program requires a 7- digit registration code made up of the digits 1,2,4,5,6,7 and 9 each number has to be used and no number can be used mor than once how many codes are possible

What are the domain and range of f(x)= -log5(x+2)