Question 175227
The area of the triangle is the base times the height divided by 2, or {{{xy/2}}}, so the Area function is {{{A(x)=(8x + x^2 - x^5)/2}}}.  The first derivitive of the Area function: {{{dA(x)/dx=8 + 2x - 5x^4}}}, set equal to zero will yield the x coordinate of the extreme point.