It is proved that XLN [(1 + x) / (1-x)] + cos x is greater than or equal to 1 + (x ^ 2) / 2 when (- 1 + x) / (1-x)]

It is proved that XLN [(1 + x) / (1-x)] + cos x is greater than or equal to 1 + (x ^ 2) / 2 when (- 1 + x) / (1-x)]

I have a method, but it's troublesome. You can refer to it
Let g (x) = XLN [(1 + x) / (1-x)] + cos X-1 - (x ^ 2) / 2
Then G '(x) = ln (1 + x) + X / (1 + x) - ln (1-x) + X / (1-x) - sinx-x
And G '(x) = 1 / (1 + x) + (1 + x-x) / (1 + x) ^ 2 + 1 / (1-x) + (1-x + x) / (1-x) ^ 2-cosx-1
It can be seen from G '(x) that when x is at (- 1)