Given: F (x) = 3x ^2 + 1, G (x) = 2x - 3, H (x) = x

H - 1 (x) =

x

1/x

-x

If I understand right you want the inverse of H (x)

H (x) = x

y=x

to calculate the inverse, isolate x, which is already the case, switch x and y, which doesn't change anything and that is your new function

the inverse is the same function in this case

so H⁻¹ (x) = x