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华东师大版八年级上册数学书习题12.2答案

1习题12.2第1题答案

140a5

2 -132a23

3162x6

4x4y2.

2习题12.2第2题答案

解:2.5×103×2.3×106=5.75×109(千克),

即总重约为5.75×109千克.

3习题12.2第3题答案

解:(1-3x·(2x2-x+4

=-3x·2x2+3x·x-3x·4

 =-6x3+3x2-12x

25/2xy· -x3y2+ 4/5x2y3

=5/2xy·x3y2 +5/2xy·4/5x2y3

=5/2 x4y3+2x3y4

4习题12.2第4题答案

解:(1)(1/2x+1-3x3/2x-2

=1/2x2+x-9/2x2+6x-4x2+7x.

2y2y-1+2yy2-2y+3

=y3-y2+2y3-4y2+6y

=3y3-5y2+6y.

5习题12.2第5题答案

1)(x+5)(x-6=x2-6x+5x-30=x2-x=30.

2 2x+1)(2x+3

=4x2+6x+2x+3

= 4x2+8x+3.

3)(3x+4 3x-4

=9x2-12x+12x-16

=9x2-16.

4)(9x+4y2

=9x+4y)(9x+4y

=81x2+36xy+36xy+16y2

= 81x2+72xy+16y2.

6习题12.2第6题答案

解:(1)(3x-1)(2x2+3x-4

=6x3+9x2-12x-2x2-3x+4

=6x3+7x2-15x+4.

2)(x+2y)(x2-2xy+4y2

=x3-2x2y+4xy2+2x2y-4xy2+8y3

 =x3+8y3.

华东师大版八年级上册数学书答案

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