# Using Vlookup formulas to populate an equation

#### yappsta

##### New Member
I have got five different power equation values from a log graph for different trend lines.

Which equation I apply depends on type of room I am calculating for.

Equation structure Y = mx^b

I have got m and c in a 1 table.

x is a parameter that varies in each of the other tables I am trying to calculate from.

I have tried a couple of different formulas but no good.

=IF(Y6="","",VLOOKUP(Y6,N18:Q21,3,FALSE)*AA6^(VLOOKUP(Y6,N18:Q21,4,FALSE)))

and

=SUMPRODUCT(Y6:Y9=N17:N21,P17:P21,AA6:AA9,Q17:Q21)

Example of tables, the first of which I have many to populate.

 x answer t.1 0.5 5 t.2 0.7 7 t.3 0.9 9 t.4 1.2 11

<tbody>
</tbody>

The second one has the values I need to use for calculations
 m b t.1 0.15 0.43 t.2 0.2 0.38 t.3 0.25 0.33 t.4 0.309 0.296 t.5 0.52 0.206

<tbody>
</tbody>

Any help would be most welcome.

Cheers

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#### yappsta

##### New Member
Don't worry, sorted it. I was being a lemon

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