When X = 3 , the slope of the function f -LRB- x -RRB- = 4 + x + 2x ^ 2 is ?
Set X is the domain of two functions -LSB- math -RSB- f -LRB- x -RRB- = x ^ 2 − x − 4 -LSB- / math -RSB- , -LSB- math -RSB- g -LRB- x -RRB- = 2x ^ 3 − 9x -LSB- / math -RSB- . If -LSB- math -RSB- f = g -LSB- / math -RSB- , what is the maximum number of the elements of -LSB- math -RSB- X ? -LSB- / math -RSB-