Accounting Question

What do you mean by cost function and for what purpose does it serve for? What are the various methods used to estimate cost functions? Explain each method with suitable numerical examples.

(Above is the question and these are the 7 methods the dr gave us for the second part of the question )

1. Engineered 2. Account Analysis 3. Two Point 4 High Low 5 Scattered 6. Regression 7 Learning curve. I need a clear and detailed answer.