1. The problem statement, all variables and given/known data Why is [tex] \nabla f = \lambda \nabla g [/tex] where f is the function you want to find the extrema of and g is the contraint? Also how would you identify the above in the following Determine the least real number M such that the inequality [tex] |ab(a^2-b^2) + bc(b^2-c^2) + ca(c^2-a^2)|\le M(a^2 + b^2 + c^2)^2[/tex] holds for all real numbers a, b and c. 3. The attempt at a solution It is the first part of the problem which I cannot do so there is no working to show You have to minimise M but subject to what? Also, there is no explicit definition for M, only the inequality.