Question 145705
f(1)=1+5+6=12
f(2)=4+10+6=20
f(4)=16+20+6=42
f(8)=64+40+6=110
f(16)=256+80+6=342

From calculus we will know that the slope is given by f'(x)=2x+5. That is to say, each increase in x results in a growing increase in y, and it grows at the aforementioned rate.

Also, note the differences between values.
8->22->68->232, the differences are growing larger by each increase in x.