find the max and min : y = x^3 - 8x^2 +61

max : dy/dx = 3x^2 - 16X ; dy/dx = 0

0=x(3x-16)

x = 5.33 y = -14.9

min : d2y/dx2 = 9x - 16 ; d2y/dx2 = 0

0=9x-16

x= 1.78 y = 41.3

its wrong ... im not sure what i did wrong though ( 3 significant digits btw)