【速来124道初二下数学计算题及答案一元一次不等式(组)、因-查字典问答网
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  【速来124道初二下数学计算题及答案一元一次不等式(组)、因式分解、分式(方程)求速度!】

  速来124道初二下数学计算题及答案

  一元一次不等式(组)、因式分解、分式(方程)求速度!

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2019-05-15 00:02
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程龚

  ①5√8-2√32+√50

  =5*3√2-2*4√2+5√2

  =√2(15-8+5)

  =12√2

  ②√6-√3/2-√2/3

  =√6-√6/2-√6/3

  =√6/6

  ③(√45+√27)-(√4/3+√125)

  =(3√5+3√3)-(2√3/3+5√5)

  =-2√5+7√5/3

  ④(√4a-√50b)-2(√b/2+√9a)

  =(2√a-5√2b)-2(√2b/2+3√a)

  =-4√a-6√2b

  ⑤√4x*(√3x/2-√x/6)

  =2√x(√6x/2-√6x/6)

  =2√x*(√6x/3)

  =2/3*|x|*√6

  ⑥(x√y-y√x)÷√xy

  =x√y÷√xy-y√x÷√xy

  =√x-√y

  ⑦(3√7+2√3)(2√3-3√7)

  =(2√3)^2-(3√7)^2

  =12-63

  =-51

  ⑧(√32-3√3)(4√2+√27)

  =(4√2-3√3)(4√2+3√3)

  =(4√2)^2-(3√3)^2

  =32-27

  =5

  ⑨(3√6-√4)?

  =(3√6)^2-2*3√6*√4+(√4)^2

  =54-12√6+4

  =58-12√6

  ⑩(1+√2-√3)(1-√2+√3)

  =[1+(√2-√3)][1-(√2-√3)]

  =1-(√2-√3)^2

  =1-(2+3+2√6)

  =-4-2√6

  (1)5√12×√18

  =5*2√3*3√2

  =30√6;

  (2)-6√45×(-4√48)

  =6*3√5*4*4√3

  =288√15;

  (3)√(12a)×√(3a)/4

  =√(36a^2)/4

  =6a/4

  =3a/2.

  5.

  x^2(y+z)^2-2xy(x-z)(y+z)+y^2(x-z)^2

  =[x(y+z)-y(x-z)]^2

  =(xz+yz)^2

  =z^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+b)^2-c^2+a^2-(b-c)^2

  =(a+b+c)(a+b-c)+(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

  =(x^2+x)(x^2+x-1)-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)

  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)+5/4(8)-3.75+(+5/4)+(-1.5)

  5.

  x^2(y+z)^2-2xy(x-z)(y+z)+y^2(x-z)^2

  =[x(y+z)-y(x-z)]^2

  =(xz+yz)^2

  =z^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+b)^2-c^2+a^2-(b-c)^2

  =(a+b+c)(a+b-c)+(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

  =(x^2+x)(x^2+x-1)-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)

  a^3-2b^3+ab(2a-b)

  =a^3+2a^2b-2b^3-ab^2

  =a^2(a+2b)-b^2(2b+a)

  =(a+2b)(a^2-b^2)

  =(a+2b)(a+b)(a-b)

  2.

  (x^2+y^2)^2-4y(x^2+y^2)+4y^2

  =(x^2+y^2-2y)^2

  3.

  (x^2+2x)^2+3(x^2+2x)+x^2+2x+3

  =(x^2+2x)^2+4(x^2+2x)+3

  =(x^2+2x+3)(x^2+2x+1)

2019-05-15 00:07:47

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