Plz i don’t remember the formula we did this so long ago

Adaylily farm sells a portion of their daylilies and allows a portion to grow and divide. the recursive formula an=1.5(an-1)-100 represents the number of daylilies, a, after n years. after the fifth year, the farmers estimate they have 2225 daylilies. how many daylilies were on the farm after the first year?

What expression is equivalent to 1/2(2+3x-6)

Could somebody me with this radical simplification?