x0=2
x0 = 2
lim(h→0)f(x0+h)-f(x0-2h))/h = 3*lim(h→0)f(x0+h)-f(x0-2h))/3h = 3*f'(x0)=6/5
所以f'(x0)=2/(1+2x0)=2/5
得到x0 = 2
f(x) = ln(1+2x)
f'(x) =2/(1+2x)
lim(h→0)[ f(x0+h)-f(x0-2h) ]/h=6/5 (0/0)
lim(h→0)[ f'(x0+h)+2f'(x0-2h) ]=6/5
3f'(x0) =6/5
f'(x0)=2/5
2/(1+2x0) = 2/5
1+2x0=5
x0=2