This is an extension to the question asked in the forums a few years ago:
Excel produces scatter diagrams for sets of pair values. It also gives the option of producing a best fit trendline and formula for the trendline. It also produces bubble diagrams which take into consideration a weight provided with each value. However, the weight has no influence on the trendline or formula. Here is an example set of values, with their mappings and weights.
Value Map Weight
0 1 10
1 2 10
2 5 10
3 5 20
4 6 20
5 1 1
I have used the formula that brettDJ offered:
=INDEX(LINEST(B2:B7*C2:C7^0.5,IF({1,0},1,A2:A7)*C2:C7^0.5,TRUE,TRUE),3,1)
However, I could not understand why we used the ^0.5 here to sqrt the weights. The original question is here