The function f is defined f:x = 1- 6x -3x^2

1. evaluate ff(-2)

2. Calculate the exact values of x which map onto themselves under the function f.

ok i could do the first one(reletively simple) BUT the 2nd one i dont understand the question and cant do. CAN anyone explain what is meant by the 2nd question?????

Also this to

3. Determine the range of f

4. Explain why f has and inverse.

Question 2 ,3 and 4 i basically just dont understand can anyone explain them???