deletions | additions       diff --git a/begin_flushleft_begin_align_S_2__1.tex b/begin_flushleft_begin_align_S_2__1.tex  index 8b91607..3eea3f6 100644  --- a/begin_flushleft_begin_align_S_2__1.tex  +++ b/begin_flushleft_begin_align_S_2__1.tex 
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&= \left< I_{signal}^2 - 2I_{signal}I'_{signal} + (I')_{signal}^2 + I_{noise}^2 - 2I_{noise}I'_{noise} + (I')_{noise}^2 \right> + \left< 2I_{signal}I_{noise} - 2I_{signal}I'_{noise} - 2I_{noise}I'_{signal} - 2I'_{signal}I'_{noise} \right> \\   &= \left< \left[ I_{signal} - I'_{signal} \right]^2 + \left[ I_{noise}^2 - I'_{noise} \right]^2 \right> + \left< 2I_{signal}I_{noise} - 2I_{signal}I'_{noise} - 2I_{noise}I'_{signal} - 2I'_{signal}I'_{noise} \right> \\  &= \left< \left[ I_{signal} - I'_{signal} \right]^2 \right> + \left< \left[ I_{noise}^2 - I'_{noise} \right]^2 \right> + \left< 2I_{signal}I_{noise} - 2I_{signal}I'_{noise} - 2I'_{signal}I_{noise} - 2I'_{signal}I'_{noise} \right> \\  &= \left< \left[ I_{signal} - I'_{signal} \right]^2 \right> + \left< \left[ I_{noise}^2 - I'_{noise} \right]^2 \right> + \left< 2I_{signal}I_{noise} - 2I_{signal}I'_{noise} - 2I'_{signal}I_{noise} - 2I'_{signal}I'_{noise} \right> \\  &\approx \left< \left[ I_{signal} - I'_{signal} \right]^2 \right> + \left< \left[ I_{noise}^2 - I'_{noise} \right]^2 \right>\\  &\approx S_{2(signal)} + S_{2(noise)}\\  \end{align*}