MATLAB filters, frequencies and wavelength -- 2

Job ID: 34393613

Budget: £10 – £20 GBP

Hi,

If graph is like quadratic. What type of filters can be used?

For example , there are three X variables named X1, X2 and X3.
X2 gives the maximum y value where as X1 and X3 gives lower value. What types of filter can be used to neutralise the graph. That is, both X1 or X3 showing similar value to X2.
Can bandpass filter be used or it will stop the X1 and X3 value?

I just want to know the theorotical knowledge for know. Happy to work practically if i believe, the freelancer can do my work on MATLAB.