(1)当b=-12时,f(x)=x²-12ln(x+1) (x>-1)
f'(x) =2x-12/(x+1)=2(x+3)(x-2)/(x+1)
令f'(x)=0 可得:x₁= -3(舍) x₂=2
当x∈(1,2)时,f'(x)0且g(-1)>0
由以上两式解得0
(1)当b=-12时,f(x)=x²-12ln(x+1) (x>-1)
f'(x) =2x-12/(x+1)=2(x+3)(x-2)/(x+1)
令f'(x)=0 可得:x₁= -3(舍) x₂=2
当x∈(1,2)时,f'(x)0且g(-1)>0
由以上两式解得0