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一、选择题 (本大题满分 3 6分 ,每小题 3分 )1 .下面四个实数中 ,是无理数的是 ( ) .Ａ .-23 Ｂ .-3 .1 4 Ｃ .4 Ｄ .π2 .下列计算正确的是 ( ) .Ａ .( -4ｘ) ( 2ｘ2 +3ｘ -1 ) =-8ｘ3-1 2ｘ2 -4ｘＢ .(ｘ +ｙ) (ｘ2 +ｙ2 ) =ｘ3+ｙ3Ｃ .( -4ａ -1 ) ( 4ａ -1
First, the multiple-choice questions (the big questions out of 3 6 points, 3 points for each small question) 1. The following four real numbers, is an irrational number is () .A .-23 B .-3 .1 4 C .4 D . Π2. The following calculations are correct () .A.( -4x) (2x2 +3x -1) =-8x3-1 2x2 -4xB .(x +y) (x2 +y2) =x3+y3C .( -4a -1 ) ( 4a -1