The question I faced is as follows:-
Consider Runge's function. $f(x)= \frac{1}{1+x^2}$
Compute and graph the interpolating polynomials (atop a graph of Runge's function itself) of with 5 equally spaced points in the interval [-5,5].
Does this mean that I have to compute and graph Lagrange interpolation for y=f(x) and x=[-5,-2.5,0,2.5,5] and then graph f(x)?
I'm confused about getting y values for a given number of equally spaced points.
Yes. I believe you need to compute and graph Lagrange (or Newton, or any other method) interpolation for x=[-5,-2.5,0,2.5,5], y=f(x), where y is obtained by plugging the five x values into Runge's function. Then graph Runge's function together with the interpolation polynomial.