some of the recipes call for 12x8, 11x7, can i put it in 13x9.

Sure, you will just need to adjust the baking time...the bigger pan should bake a bit faster, so keep an eye on whatever you are baking so it does not overbake.

thank you very much.

I do it all the time... sometimes the one I want it just in the dishwasher and I'm too lazy to wash by hand. Like l4l says, just watch the baking times.