Brown dry yellowy leaves HELP

This is my first grow and i dont know what this problem is. Is it nute burn or light burn please someone help me.
The leaves seem to be going brown and mottled then really dry.

need more info and better pic
how old are they
grow temps
what you feeding and what strength

R these photos good enough for you mate im growing under a 250 wt hps lamp. temp in grow box is around 28-30 degrees all the time. just using basic miracle grow feed until flowering starts. They are now two weeks old from when i germinated them.

two weeks is a bit young for feeding just water, if they look like they need feeding pot up with some good soil. How much feed did you give them? this is why you have browning.
Your temps are a bit high try to keep them under 28c

sounds like you started feeding too soon. flush them out.