Find the absolute maximum and absolute minimum values, if any, of the function. (If an answer does not exist, enter DNE.)

f(x) = x2 − x − 5 on [0, 5]

Come someone please show me how to do these problems? I'm lost

1 answer

Set the derivative equal to zero and see if there is a solution in that interval.

2x - 1 = 0

x = 1/2

Now plot it (or take the second derivative f''(x) = 2) to see if that is a maximum or a minimum.

If you have not learned what a derivative is, complete the square of the f(x) function.

f(x) = (x - 1/2)^2 - 5 1/16 = 0

Obviously the lowest value of f(x) is obtained at x = 1/2