I was helping somebody answer some questions when this wild question appears. It looks like this:
Let $f$ be the function given by $f(x)=x^2 - 2x +3$. The tangent line to the graph of $f$ at $x = 2$ is used to approximate values of $f(x)$. What might be the greatest value of $x$, where the error resulting from tangent line approximations is less than $0.5$?
My work
I honestly don't know how to answer it. I found this question when my friend was studying for some licensing exams.....so I turned here for help.
How do you answer the above question?
$(2,3)$ is a touching point and $y-3=2(x-2)$ or $y=2x-1$ is an equation of the tangent.
Thus, $$|x^2-2x+3-(2x-1)|\leq0.5$$ or $$|x-2|\leq\frac{1}{\sqrt2},$$ which gives $$x_{max}=2+\frac{1}{\sqrt2}.$$