Let f(x)=(x+3)2(x-2)3, x [-4,4]. If M and m are the maximum and minimum values of f, respectively in [-4,4], then the value of M-m is
- 108
- 392
- 608
- 600
Answer
(3) 608
Solution
f'(x)=2(x+3)(x-2)3+3(x+3)2(x-2)2
=5(x+3)(x+1)(x-2)2
[figure]
∵ absolute extremes on [-4,4] are among end points and critical points:
f(-4)=(1)(-216)=-216, f(-3)=0, f(-1)=(4)(-27)=-108
f(2)=0, f(4)=(49)(8)=392
M=392, m=-216
∴ M-m=392+216=608
Answer: (3)