Find Log2FC values from qPCR data

Question

[SKY]

Hello!

I have got Fold Change (FC) values for a gene for 3 Biological Replicates.

1.Which is the correct method to calculate Log2FC ? Case1 or Case2? Which case is incorrect and why?

1. If Case1 is correct? Using which column do i calculate the standard deviation/error?

I want to make a bar plot using Log2FC (Y axis) and Gene name (X axis) with error bars.