I have two columns, say `x`

and `f(x)`

. I want to get the coefficients of the second degree equation after doing the polynomial regression in Excel VBA.

I’m a rookie in Excel VBA and have no clue what to do.

For example-

x y

-1 -1

0 3

1 2.5

2 5

3 4

5 2

7 5

9 4

The coefficients for the equation `f(x)=a*x^2+b*x+c`

will be

```
a= -.008571
b= 0.99555
c= 1.648439.
```

I got the coefficients using THIS website

In terms of using code for this, use `LINEST`

, one way below

```
Sub Quaddy()
Dim X
X = Application.Evaluate("=linest(b1:B8,A1:A8^{1,2})")
MsgBox "Equation is y=" & Format(X(1), "0.
```### Answer：

") & "x2+" & Format(X(2), "0.### Answer：

") & "x+" & Format(X(3), "0.### Answer：

")
End Sub

This is shown in the Excel chart below

Tags: excelexcel, vba