Is -LSB- math -RSB- y = \ sqrt -LCB- 5 -RCB- x ^ 2 - 3x + 1 -LSB- / math -RSB- a polynomial function ?
If a function -LSB- math -RSB- f -LRB- x -RRB- -LSB- / math -RSB- is defined as -LSB- math -RSB- f -LRB- x -RRB- = x ^ 3 + 3x + 1 -LSB- / math -RSB- , then what is -LSB- math -RSB- f ^ -LCB- -1 -RCB- -LRB- x -RRB- -LSB- / math -RSB- ?