



 
Christy, What you have done so far is correct. What you do next depends on what you know. Is this a calculus problem? If so the differentiate the function A(x) = 4x  x^{2} and solve A'(x) = 0 to find any critical points. This gives x = 2 and what remains is to show that x = 2 actually yields a maximum. If this is not a calculus class then you might have an expression that tells you where the maximum or minimum of a parabola appears. You might notice that the parabola A = x(x  4) crosses the xaxis at x = 0 and x = 4 and then conclude by the symmetry of the parabola that the maximum must appear half way between 0x = 0 and x = 4. If this doesn't help then write back. Harley  


Math Central is supported by the University of Regina and The Pacific Institute for the Mathematical Sciences. 