I have a question with regards to another differential problem:

why is it wrong to have the +C there? The second part of the question says for y(0)=1 find a specific formula. I know the way I have it setup with C on both sides they will always cancel off, but it seems somewhat logical considering how if it maters which side of the equation I put C on. For example, on the right it is +1 but if I left the +C and took the other away it would be -1.