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14道初一数学题40.(1-3m)/2-(2m+5)/3+(3+2m)/441.2/3(x-y)^(2n+1)*9/4(

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14道初一数学题
40.(1-3m)/2-(2m+5)/3+(3+2m)/4
41.2/3(x-y)^(2n+1)*9/4(x-y)^(2n+1)*7/15(x-y)^4n
42.(0.25a^3b^2)^2*(4a^2b)^3-3(-a^2b)^5*a^2b^2
43.解不等式:x(x-3)
14道初一数学题40.(1-3m)/2-(2m+5)/3+(3+2m)/441.2/3(x-y)^(2n+1)*9/4(
40.(1-3m)/2-(2m+5)/3+(3+2m)/4 =1/2-3m/2-2m/3-5/3+3/4+2m/4==-5/12-5m/3
41.2/3(x-y)^(2n+1)*9/4(x-y)^(2n+1)*7/15(x-y)^4n
=2/3*9/4*7/15*(x-y)^(2n+1+2n+1+4n)
=7/10(x-y)^(8n+2)
42.(0.25a^3b^2)^2*(4a^2b)^3-3(-a^2b)^5*a^2b^2
=0.25^2a^6b^4*4^3a^6b^3+3a^10b^5*a^2b^2
=4a^12b^7+3a^12b^7
=7a^12b^7
43.解不等式:x(x-3)1/3
44.3(2x-1)(x-3)-2(3x-2(2x-3) = -6x^2+5x-3
45.2008^2-2007*2009=2008^2-(2008-1)*(2008+1)=2008^2-(2008^2-1)=1
46.2(2x-7y)(7y+2x)+x^2-(-4x+5y)(-5y-4x)
=2(4x^2-49y^2)+x^2+(25y^2-16x^2)
=-7x^2-73y^2
47.(x+y)^2(x-y)^2 =((x+y)(x-y))^2 =(x^2-y^2)^2 =x^4-2x^2y^2+y^4
48.(a-2b+3c)^2 =a^2+4b^2+9c^2-4ab+6ac-12bc
49.(3a-b)^2-(3a+b)^2 =(3a-b+3a+b)*(3a-b-3a-b) =-12ab
50.a(a-1)-(a^2-b)=8,求(a^2+b^2)/2-ab的值 32
51.(-2x-1)^2*(2x-2)^2-16(x+3)^2*(x-3)^2
=(-4x^2+2x+2)^2-16(x^2-9)^2
=16x^4+4x^2+4-16x^3-16x^2+8x-16(x^4-18x^2+81)
=-16x^3+276x^2+8x-1292
52.(x+2)(x+3)(x-2)(x-3) =(x^2-4)(x^2-9) =x^4-13x^2+36
53.(a+3)(a-3)(a^2+9)-(a^2-9)^2
=(a^2-9)(a^2+9)-(a^2-9)^2
=(a^2-9)(2a^2)
=2a^4-18a^2
54.101*99*9999
=(100+1)*(100-1)*9999
=9999*9999
=(10000-1)(10000-1)
=100000000-20000+1
=99980001