[![My code and the result](https://i.stack.imgur.com/fRVKS.jpg)](https://i.stack.imgur.com/fRVKS.jpg)
I'm learning to use Texpad on my iPad starting from two hours ago. I'd like the leading + symbols to be aligned with each other. The app doesn't allow me to use `&` for additional alignment tab, so I had to use `\cr` instead. But the initial tab has to be `&`, and the 'alignment' seems to be dysfunctional because I had to put my `&` where you can see it is because that's where the result gets as close it gets to my intention.

How can I have my split lines precisely aligned at the tab without messing around with the initial one?