As written, your post is a little puzzling.

To use LINEST() you're going to need to start with both a series of X values
and a series of Y values. So you won't "Calculate the corresponding value of
Y," but you can use the regression coefficients and the constant to get
estimates of Y. If what you're really after is the Y estimates, the TREND()
function is more straightforward than LINEST() because it calculates the
equation and applies it to your X values to return the Y estimates. But if
you use LINEST(), and assuming you have Y in column A, X in column B, X^2 in
column C and X^3 in column D, start by selecting a blank range four columns
wide and five rows high, type this formula:

=LINEST(A1:A100,B1:D100,,TRUE)

and array-enter it with CTRL-SHIFT-ENTER instead of just ENTER. You can also
square and cube X in the arguments:

=LINEST(A1:A100,B1:B100^{1,2,3},,TRUE)

What do you want to compare A,B,C & D to? Zero? Something else? Use the
standard errors.

You can force the constant to zero using LINEST's third argument but in
general it's a bad idea.

--
C^2
Conrad Carlberg

Excel Sales Forecasting for Dummies, Wiley, 2005


"Dave in naigeria" <Dave in wrote in
message ...
Please can anyone help me solve this problem.

Use linest function to estimate what A,B,C & D will be, Compare them.

Y= a+bx+cx^2+dx^3

assum x=0, x=1, .................. x= 100

Calculate the corresponding value of Y. Choose any coefficient for the
constant.

Thanks and regards,
Dave