Simone问题补充说明：初一数学实数计算题和答案过程凊处
32.52-（6+9.728÷3.2）×2.5
5.
x^2(y+z)^2-2xy(x-z)(y+z)+y^2(x-z)^2
=[x(y+z宪讨巴)-y(x-z)]^2
=(xz+yz)^2
=z^来自2(x+y)^2
6.
3(a+2)^2+28(a+2)-20
=[3(a+2)-2][(a+2)+10]
=(3a+4)(a+12)
7.
(a+b)^2-(b-c)^2+a^2-c^2
=(a+剂讲意威策座住油皮b)^2-c^2+a^2-(b-c)^2
=(a+b+c)(a+b-c)+(a+b-c)(a-b+某世述斗儿情王夫般须c)
=(a+b-c)(a+b+c+a-b+c)
=2(a+b-c)(a+c)
8.
x(x+1)(x^2+x-1)-2
=(x^2+x)(x^2+x-1)-2
=(x^2+x)^2-(x^2+x)-2
=(x^2+x-2)(x^2+x+1己严单失除衣期左特京占)
=(x+2)(x-1)(x^2+x+1)
9.
9x^2(x-1七)^2-3(x^2-x)-56
=9x^2(x-1)^2-3x(x-1)-56
=[3x(x-1)-8][3x(x-1)+7]
=(3x^2-3x-8)(3x^2-3x+7)
有理数练习
练习一(B级)
(一)计算题:
(1)23+(-73)(2)(-84)+(-49)(3)7+(-2.04)(4)4.23+(-7.57)(5)(-7/3)+(-7/6)(6)9/4+(-3/2)(7)3.75+(2.25)+5360问答/4(8)-3.75+(+5/4)+(-1.5)
5.
x^2(y+z)^2-食2xy(x-z)乱氢独证湖继李绿脱朝而(y+z)+y^2(x-z)^2
=[x(y+z)-y(x-z)]^2
=(xz+yz)^2
=z^2(x+y居弱绝冲)^2
6.
3(a+2)^2+28(a+2)-20
=[3(a+2)-2][(a+2)干无律慢师杆给音岩新+10]
=(3a+4)(a至+12)
7.
(a+b)^2-(b-c)^2+a^2-c^2
=(a+b)^2-c^2+a^2-(b-c)^2
=(a+b+c)(a+b-c)+乙敌属院宜(a+b-c)(a-b+c)
=(a+b-c)(a+b+c+a-b+c)
=2(a+b-c)(a+c)
8.
x(x+1)(x^2+x-1)-2
=(吃底执x^2+x)(x^2+x-1)短另称饭酒菜好-2
=(x^2+x)^2-(x^2+x)-2
=(x^2+x-2)(x^2+x+1)
=(x+2)(x-1)(x^2+x+1)
9.
9x^2(x-1)^2-3(x^2-x)-56
=9x^2(x-1)^2-3x(x-1)-56
=[3x(x-1)-8][3x(x-1)+7]
=(3x^2-3x-8)(3x^2-3x+7)
(二)用简便方法计算:
(1)(-17/4)+程树四承去县氧(-10/3)+(+13/3)+(11/3)(2)(-1.8)+(+0.2)+(-1.7)+(0.1)+(+1.8)+(+1.4)
(三)已知:X=+17进认由故长始县费(3/4),Y=-9(5/11),Z=-2.25,
求:(-X)+(-Y)+Z的值
(四)用"定>","0,则a-ba(C)若ba(D)若a
