reciprocal simply means 1 over

the reciprocal of x is 1/x

the reciprocal of something like √x is 1/√x

inverse is the "opposite" of the function

the inverse of √x is x² since the square and the root effectively 'undo' each other

2x + 1 woudl have and inverse of ½(x - 1)

the reciprocal woudl be