[tex]f'(x)= \frac{(m+1)(1-x)(1+x)}{(x^2-x+1)^2}\\
[/tex]
1)m+1>0
x |-∞ -1 1 +∞
f(x) |1 ↓ (2-m)/3 ↑ m+2 ↓ 1
f'(x) | ------------------ 0 ++++++++0---------------
(m+2)-(2-m)/3=4
m=2
2)m+1<0
x |-∞ -1 1 +∞
f(x) |1 ↓↑ (2-m)/3 ↓ m+2 ↑ 1
f'(x) | +++++++++++ 0 --------------0+++++++++
(2-m)/3-(m+2)=4
m=-4