What are four different ways of representing functions? how can you tell if a relationship is a function?

Find an equation of the line perpendicular to the graph.

Translate the word phrase into a math expression. 15 fewer than the product of 4 and a number. (pls immediately)

Write the expression in simplified radical form. show all steps and work including any foil method work. (hint: use the conjugate. no decimal answers.) (9-2√3)/(12+√3)