Turning concave log(1+ax+y) function to convex function

Nonconvex
1

Hello,

I have a function log(1+ax+y) where a>0. Due to the logarithm this function is concave I think. I know that I can turn concave log(1+ax) to convex log(1+ae^x). Is there any trick for my function.

2

log(1+ax+y) is concave.