please help

0) Find the maxima and minima and any local maxima and local minima for the functions defined on the set of x values given. a. y=x48x2+3 defined from x=0 to x=3. b. y=3x4+8x318x2 defined from x=2 to x=2. c. y=3x4+8x318x2 defined from x=4 to x=2