/sci/ - Science & Math

Trying to do the first linear DE problem on Paul's Calc notes.

The stuff above the line is my attempt; the 25 is supposed to be a 50 according to the answer, meaning the factor of 2 I have isn't supposed to be there.

Below the line is how it's actually supposed to be done according to the site, where you don't get two of that term after integrating, but I have no idea what happens between the last two steps I wrote or why my attempt didn't work.

So, where'd I fuck up? This is calc 4 but I feel like my calc 1 knowlage is what's missing. I know I have the right integration constant.