作业帮(2x+y-1)(2x+y-1)怎么算
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(2x+y-1)(2x+y-1)怎么算
(2x+y-1)(2x+y-1)怎么算
(2x+y-1)(2x+y-1)怎么算
原式=[(2x+y)-1]²
=(2x+y)²-2(2x+y)+1²
=4x²+4xy+y²-4x-2y+1
x^3-x
=x(x^2-1)
=x(x+1)(x-1)
a^2b^2-1
=(ab+1)(ab-1)
a^4 - b^4
=(a^2+b^2)(a+b)(a-b)
3a^3-a/3
=(1/3)a(9a^2-1)
=(1/3)a(3a+1)(3a-1)
a^(n+1)-a(n-1)b^4
=a(n-1)(a^...
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x^3-x
=x(x^2-1)
=x(x+1)(x-1)
a^2b^2-1
=(ab+1)(ab-1)
a^4 - b^4
=(a^2+b^2)(a+b)(a-b)
3a^3-a/3
=(1/3)a(9a^2-1)
=(1/3)a(3a+1)(3a-1)
a^(n+1)-a(n-1)b^4
=a(n-1)(a^2-b^4)
=a^(n-1)(a+b^2)(a-b^2)
-x^2+1/4
=-(x+1/2)(x-1/2)
m^2n^4-a^4b^2
=(mn^2+a^2b)(mn^2-a^2b)
(x+2y)^2-(2x-y)^2
=(x+2y+2x-y)(x+2y-2x+y)
=(3x+y)(3y-x)
(9y^2-x^2)-(x+3y)
=(x+3y)(3y-x)-(x+3y)
=(x+3y)(3y-x-1)
2005^2-9
=2005^2-3^2
=(2005+3)(2005-3)
=2008*2002
=2008*(2000+2)
=2008*2000+2008*2
=4016000+4016
=4020016
19.91^2-0.09^2
=(19.91+0.09)(19.91-0.09)
=20*19.82
=396.4
若(2分之1x)^n-81=(4分之1x^2+9)(2分之1x+3)(2分之1x-3),那么n的值式( )
A2, B,4 C,6 D,8
(4分之1x^2+9)(2分之1x+3)(2分之1x-3)
=(x^2/4+9)(x^2/4-9)
=x^4/16-81
=(x/2)^4-81
n=4
选B
11^10-1
=(11^5+1)(11^5-1)
11^5-1
=(11-1)(11^4+11^3+11^2+11+1)
=10*(11^4+11^3+11^2+11+1)
因为11^4，11^3，11^2,11,1个位都是1
所以11^4+11^3+11^2+11+1个位是5，能被5整除
所以10*(11^4+11^3+11^2+11+1)能被50整除
又因为11^5是奇数，所以11^5+1是偶数，能被2整除
所以11^10-1能被2*50=100整除
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