MHB Solve My Constant Problem: Integral Sign + -2

[Eni]

I don’t understand how the second (-2) (in front of the integral sign) gets into the equation. Can you please help me?View attachment 8766

 

[Evgeny.Makarov]

Hi, and welcome to the forum.

It's not clear to me which equality your question is about. Besides the line "Not counting..." you post contains a single equality, the one with yellow marks in the left-hand side. This equality is correct because it simply moves the minus in front of $e^{-x}$ outside the integral, just like the text in the previous line says. Twos marked in yellow don't participate in this transformation. As for the first line, it's only half of an equation, so it is not clear what is being claimed about it.

 

[Eni]

Hi Evgeny,

Thanks, I reviewed it again and it seems I just needed "fresh eyes/mind" to look at the problem. Thanks again!