Been dealing with some issues related to analytical lab work.
A bit of frustration at people who don't seem to remember their Algebra I from middle or high school.
A quadratic equation, also referred to as second-order, is of the form
y = ax² + bx + c.
If it goes through the origin, which it will if the curve fit is forced through zero, it will be
y = ax² + bx.
It's possible that b will be zero, in which case it will be
y = ax² + c
or, if forced through zero,
y = ax².
It will never be
y = ax.
I am reminded of people I went to school with, who if they had a history teacher assign an essay and then count off for sentence fragments or misspellings, complained that that wasn't fair because it wasn't an English class. A sentence fragment is a sentence fragment. A quadratic equation is a quadratic equation. Even if you meet one in a dark alley on a stormy night, it must have an x² about it somewhere.