解方程: 2 x x - 2 - 8 x 2 - 2 x = 1
如图,在四边形ABCD中,AB=AD,AC是∠BAD的角平分线. 求证:△ABC≌△ADC.
计算:.
计算:6÷3+·(﹣5a).
计算:(2+5)(2﹣5)﹣(﹣)2.
(1)计算:+(π-3)0-tan45°; (2)计算:()÷.