Functions_1 discusses different type of relationships, one-to-one, one-to-many and many-to-one, and how to differentiate between them and which relationship is a function or not, and how to graph it. It contains principles of translation and reflection of a function. Principle of estimation of roots. Principle of sign change rule. It discusses inverse functions and its relationship with reflection. Lastly, it discusses how to combine and composite two or mor functions. All of that in simple step-by-step instructions.