Okay so first off first off I believe 4-6 is linear because it is increasing at a steady rate and 7 is exponential because it has a constant rate of growth. I’m not 100% I’m correct on that. 8 is linear, 9 is exponential.
For 4: f(x)=-1/2x + 1
5: f(x)=-2x +4
That’s all I know right now. I hope it helps a little bit