There are **21** NRICH Mathematical resources connected to **Maximise/minimise/optimise**, you may find related items under Functions and Graphs.

What is the quickest route across a ploughed field when your speed around the edge is greater?

Find all the turning points of y=x^{1/x} for x>0 and decide whether each is a maximum or minimum. Give a sketch of the graph.

Find the maximum value of n to the power 1/n and prove that it is a maximum.

Chris is enjoying a swim but needs to get back for lunch. If she can swim at 3 m/s and run at 7m/sec, how far along the bank should she land in order to get back as quickly as possible?

Which set of numbers that add to 10 have the largest product?

Can you massage the parameters of these curves to make them match as closely as possible?

Can you work out how to produce the right amount of chemical in a temperature-dependent reaction?

Make and prove a conjecture about the cyclic quadrilateral inscribed in a circle of radius r that has the maximum perimeter and the maximum area.

A ladder 3m long rests against a wall with one end a short distance from its base. Between the wall and the base of a ladder is a garden storage box 1m tall and 1m high. What is the maximum distance. . . .

Three fences of different lengths form three sides of an enclosure. What arrangement maximises the area?

A 10x10x10 cube is made from 27 2x2 cubes with corridors between them. Find the shortest route from one corner to the opposite corner.

The graph represents a salesman’s area of activity with the shops that the salesman must visit each day. What route around the shops has the minimum total distance?

Can you make sense of information about trees in order to maximise the profits of a forestry company?

A point moves around inside a rectangle. What are the least and the greatest values of the sum of the squares of the distances from the vertices?

Christmas trees are planted in a rectangular array. Which is the taller tree, A or B?

There are 12 identical looking coins, one of which is a fake. The counterfeit coin is of a different weight to the rest. What is the minimum number of weighings needed to locate the fake coin?

If x + y = -1 find the largest value of xy by coordinate geometry, by calculus and by algebra.

Given that u>0 and v>0 find the smallest possible value of 1/u + 1/v given that u + v = 5 by different methods.

Investigate the graphs of y = [1 + (x - t)^2][1 + (x + t^)2] as the parameter t varies.

Four rods are hinged at their ends to form a quadrilateral. How can you maximise its area?

If x, y and z are real numbers such that: x + y + z = 5 and xy + yz + zx = 3. What is the largest value that any of the numbers can have?