What is the derivative of 8x2?

Answer 1

The derivative of a function tells you how it changes in response to a change in a specific variable. The derivative of a linear function (like y = 2x + 3) with respect to its independent variable is the slope of the line (in this case, two): how much the line rises or falls when "x" changes by one.

The expression 8x2 does not involve any variables, and thus never changes. Its derivative is therefore zero. There is no variable involved, so the result is always 16. Changing the input variable (of which is there is none) has zero effect on the answer.