计算:(1)(﹣17)+59+(﹣37)(2)﹣43÷5×(3)﹣1.53×0.75+0.53×﹣3.4×0.75(4)(+1.75)﹣|﹣|+(+1.05)+(﹣)﹣(﹣2.2)(5)﹣(1﹣0.5)÷(6).
计算:.
计算:6÷3+·(﹣5a).
计算:(2+5)(2﹣5)﹣(﹣)2.
(1)计算:+(π-3)0-tan45°; (2)计算:()÷.
已知,如图,点B、E、C、F四点在同一条直线上,AB∥DE,AB=DE,AC、DE相交于点O,BE=CF.求证:AC=DF.