I have a linear line on a graph that intersects the y axis at 0.1 and the x axis at 1. Very simple, however for the life of me I can't remember the process for finding the function expression.
By trial and error I have found that $y=-\frac{1}{x}+0.1$ in this case but I am wondering if someone could tell me a step by step process for coming up with the function expressions in general, from less obvious graphs.
The intercept-intercept form of a line is $$\frac{x}a + \frac{y}b = 1$$ where $a$ is the $x$-intercept and $b$ is the $y$-intercept.
In functional form, this is $$y = -\tfrac{b}a x + b$$
By the way, your equation is wrong: it should be $$y = -0.1x + 0.1$$