不等式2x-4
(1)原式=2ab 2 c 2 abc=4a 2 b 3 c 2 . (2)原式=3x 2 ﹣6x+x 2 +3x﹣2x﹣6 =4x 2 ﹣5x﹣6. (3)原式=(2a) 2 ﹣(3b) 2 +a 2 ﹣2a 3 b+(3b) 2 =4a 2 ﹣9b 2 +a 2 ﹣6ab+9b 2 =5a 2 ﹣6ab. (4)原式=[x 2 +2xy+y 2 ﹣(x 2 ﹣2xy+y 2 )]÷2xy, =(x 2 +2xy+y 2 ﹣x 2 +2xy﹣y 2 )÷2xy, =4xy÷2xy, =2. 解析看不懂?
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