I dont understad these questions for which value s of a does the curve y x

ave a horizontal tangent line at x = 1 ? (Without using differentiation rules) For each statement, explain why it must be true, or use an example to show that it can be false. a)If y = f ( x ) has a horizontal tangent line at x = 1 then y = g ( x ) , where g ( x ) = f ( x − 1 ) + 1 , has a horizontal tangent line at x = 2 . b)A tangent line always has exactly one point in common with the graph of the function.