Finding Graph Values

[Saxman]

I have the following data and have created a quadratic graph in some graphing
software.

I need to find the value of y when given the value of x. Although the software does
this by entering the value in a field, can this been done in Excel for simplicity,
so that my data can be presented in one workbook?

For reference, here is the chart data.

Quadratic Fit: y=a+bx+cx^2
Covariance Matrix:
0.072191584 -1.2817125e-006 2.409272e-012
-1.2817125e-006 4.8656751e-011 -9.9175004e-017
2.409272e-012 -9.9175004e-017 2.1735336e-022

Coefficient Data:
a = 23.245844
b = 0.00084010365
c = -5.6299897e-011


x y
0 25
1000 26
2000 27
3000 28
4000 28
5000 29
6000 30
7000 31
8000 32
9000 32
10000 33
20000 41
30000 49
40000 57
41000 58
42000 59
43000 60
44000 60
45000 61
46000 62
47000 63
48000 64
49000 65
50000 66
100000 106
300000 268
500000 430


--

 

[Saxman]

x y
0 25
1000 26
2000 27
3000 28
4000 28
5000 29
6000 30
7000 31
8000 32
9000 32
10000 33
20000 41
30000 49
40000 57
41000 58
42000 59
43000 60
44000 60
45000 61
46000 62
47000 63
48000 64
49000 65
50000 66
100000 106
300000 268
500000 430

It looks like the FORECAST function will do similar from the given data above.
There is an example in the help files. From the function below which is in cell
B31, how do I create a data entry cell without have to alter the value in the
function below? (In this example 10000).

=FORECAST(30,A2:A29,B2:B29)+FORECAST(10000,C3:C29,B3:B29)

--

 

[Jon Peltier]

Put the value you want to use into another cell, say E1, and use this cell
reference in the formula:

=FORECAST(30,A2:A29,B2:B29)+FORECAST(E1,C3:C29,B3:B29)

- Jon