...hi i've got a question and i'm coming up with a slightly different answer to my textbook so could someone please show me what i'm doing wrong:

find the set of values of x for which the function h, where is increasing

well the first thing i did was expand the brackets and differentiate:

then

then arranged it like so:

when you divide both sides of an inequality by a negative value, the direction of the inequality changes.

the books answer is

any help would be appreciated, thanks