Where is the error in writing the formula?

Question

MATLAB

k=4;x=-1.5;c=0.13;a=0.75;b=5.55
I tried different options. But the answer doesn't seem right to me. I would like to compare with your results.

Answer 1

and where is the formula itself, in which you need to look for an error? I'm sure if you just check yourself once, that will be enough.