[Math] What does the math symbol $\propto$ mean

Question

I came across this symbol in my engineering class and I have never seen it before. Anyone know this?

Answer 1

It typically means proportional to. Such that

If $$y=cx$$ for some constant $c$ we say

$$y\propto x$$ so that when x grows, y grows proportionally by the ratio $c$

Alternatively inverse proportionality is when

$$y=c\frac{1}{x}$$ so that when x gets smaller, y gets bigger proportionally by $c$

$$y\propto \frac{1}{x}$$ to my knowledge there isn’t a symbol specifically for inverse proportionality and $$y\propto \frac{1}{x}$$ is used instead