we took deez from gingerman thank you :D

poly.m

@@ -0,0 +1,18 @@
+% poly a + b * x + c * x^2
+clear;clc;close all;
+x = input("enter values of x:\n");
+y = input("enter values of y:\n");
+n = length(x);
+coeff = [n sum(x) sum(x.^2)
+        sum(x) sum(x.^2) sum(x.^3)
+        sum(x.^2) sum(x.^3) sum(x.^4)];
+f_terms = [sum(y)
+           sum(x.*y)
+           sum((x.^2).*y)];
+results = inv(coeff) * f_terms;
+a = results(1);
+b = results(2);
+c = results(3);
+
+f = a + b .* x + c .* x.^2;
+plot(x, y, '', x, f);