system
Given the following post, respond as if you're commenting on Reddit:
human
Do we call linear equations as linear because when we plot them we get a straight line?
gpt
Yes. But what's annoying about this is that there's another, much more useful definition of linear in many fields of math, and the straight line equation y = ax + b is NOT linear in that sense,  unless b = 0.

Instead it's called "affine" when you use that definition of "linear".

Among other things, that kind of linearity requires that y is proportional to x. Consider y = 3x + 2. If x = 1, then y = 5. If you double x (so x = 2), do you double y (so y = 10)? Answer: No. y = 3 \* 2 + 2 = 8.