计算:
(1) a ( a + 2 b ) - ( a + b ) ( a - b )
(2) ( x + 2 x - 3 + x + 2 ) ÷ x 2 - 4 x + 4 x - 3
计算
计算(2+)(2﹣)﹣
(1)计算:; (2)解方程: