What is the derivative of y with respect to x if y = 2/x4 a. 8/x5 b. 8/x3 c. -8/x5 < think it's this one. not sure. d. -8/x3

You're correct, the answer is C.

Given any function of the form , then the derivative of y with respect to x () is written as:


In which  is any constant, this is called the power rule for differentiation.

For this example we have , first lets get rid of the quotient and write the expression in the form :


Now we can directly apply the rule stated at the beginning (in which ):


Note that whenever we differentiate a function, we simply "ignore" the constants (we take them out of the derivative).