# How to make linear quadratic, etc fit

Please can anybody help me to get a linear, and quadratic fit. I have a line from numerical calculations (Refs), and I want to fit the data(max) with (Refs). I tried linear fit but I have a problem when I use it for two variables and also for the quadratic fit.

I used fl[x_, y_] = Normal@LinearModelFit[tab, a1r (y - y0) + b1r (x - x0), {a1r, b1r}, {x, y}] , and x0=0.3459; y0=0.4478, but it doesn't work.

Or is there a way to use this (y-y0)=m(x-x0), m is the slope of the numerical line(Refs) to make fitting.

my data is many, I don't know how to post all, I just post some.

  tab= {{0.025, 0.075, -0.0129036}, {0.0255, 0.075, -0.00949092}, {0.026,
0.075, -0.00607024}, {0.0265, 0.075, -0.00264156}, {0.027, 0.075,
0.000795063}, {0.0275, 0.075, 0.00423958}, {0.028, 0.075,
0.00769193}, {0.0285, 0.075, 0.0111521}, {0.029, 0.075,
0.01462}, {0.0295, 0.075, 0.0180955}, {0.03, 0.075,
0.0215787}, {0.025, 0.0755, -0.0131653}, {0.0255,
0.0755, -0.00975679}, {0.026, 0.0755, -0.00634031}, {0.0265,
0.0755, -0.00291584}, {0.027, 0.0755, 0.000516539}, {0.0275, 0.0755,
0.00395679}, {0.028, 0.0755, 0.00740485}, {0.0285, 0.0755,
0.0108607}, {0.029, 0.0755, 0.0143242}, {0.0295, 0.0755,
0.0177954}, {0.03, 0.0755, 0.0212742}, ......}

Refs = ListContourPlot[tab, FrameLabel -> {"x", "y"},
ContourStyle -> Blue  , ContourShading -> False, Contours -> 1]

max = {{0.023919999999999997, 0.05784}, {0.023919999999999997,
0.05824000000000001}, {0.024319999999999998,
0.058640000000000005}, {0.024319999999999998,
0.05904000000000001}, {0.024319999999999998,
0.05944000000000001}, ...}

x0=0.3459;
y0=0.4478
x = max[[All, 1]];
y = max[[All, 2]];
p = ListLinePlot[max, PlotRange -> {{0.025, 0.03}, {0.075, 0.08}},
BaseStyle -> {Red}]

Show[Refs, p]