I have a question and I hope someone can help me out

I was looking at some airfares to some places like Memphis and Salt Lake City. Well if i book a flight from MCI to Dallas it's 135 with a layover in Memphis on NW
But if I book a flight from MCI to Memphis it's 288, so my question is, can i just book the MCI to Dallas flight and get off in Memphis and not take Dallas Connection and the same on the way back

I was just wondering if you can do this

I have also found cheaper airfare to SLC by doing this