解方程组和不等式组:
(1) x + y = 0 2 x - y = 3 ;
(2) 3 x + 6 > 0 x - 2 < - x .
(1)计算:; (2)因式分解:.
计算:(1) (2)
(本题满分8分,每题4分)计算:(1)+2sin45°- (2)2(a+1)-(3-a)(3+a)-
计算(每小题3分,共9分)(1) (2)-(x-1)(x-2)(3)用简便方法计算:20142﹣4030×2014+20152
(每小题3分,共6分)计算:(1) (2)