12 foot span load bearing wall 2x4,s.this is first floor carrying 2x10 joist for the second floor bedrooms. House is 25 foot wide cape.I plan using 9.25 or micro lam beams two of either.will two 9.25 cover the load

You need to provide more information in order to do the calculations correctly.

Basically, you are looking for the tributary area that is supported by the micro-lam and you multiply the live loads and dead loads of the floor and roof above that it will support. You take the total and compare it to standard beam sizing charts to get the proper size.

Double 2x12 header with footing and lolly column at mid span of 30 feet.

U could get micro beam to do span without column, but I do not know size. Would have to check with manufacturer.

Chuck