因式分解1.x^2+x+4分之1 2.20xy-4x^2-25y^2 3.4(x+y)^2-8(x+y)+4 4.-4分之1x^2+3分之1xy-9分之1y^2 5.(a^2+b^2)^2-4a^2b^2 6.(x^2+4分之1)^2-2x(x^2+4分之1)+x^2 7.x^3+x^2-2006*2007x 8.a^2n+2-a^2n 9.(2分之1a+3分之2b-4分之3c)^2-(2分之1a-3分之2b-4分之3c)^2 10.(50又11分之1)^2-(49又11分之10)^2 11.(10+100分之1+0.001)^2-(0.01+1000分之1-10)^2
(1)x^2+x+1/4=(x+1/2)^2
(2)20xy-4x^2-25y^2= -(2x-5y)^2
(3)4(x+y)^2-8(x+y)+4
=4[(x+y)^2-2(x+y)+1]
=4(x+y+1)^2
(4)-4分之1x^2+3分之1xy-9分之1y^2
=-(1/2x+1/3y)^2
(5)(a^2+b^2)^2-4a^2b^2
=a^4+2a^2b^2+b^4-4a^2b^2
=a^4-2a^2b^2+b^4
=(a^2-b^2)^2
(6)(x^2+4分之1)^2-2x(x^2+4分之1)+x^2
=(x^2+1/4-x)^2
=[(x-1/2)^2]^2
=(x-1/2)^4
(7)x^3+x^2-2006×2007x
=x(x^2+x-2006×2007)
=x(x+2007)(x-2006)
(8)a^2n+2-a^2n
=a^2n(a^2-1)
=a^2n(a+1)(a-1)
(9)(2分之1a+3分之2b-4分之3c)^2-(2分之1a-3分之2b-4分之3c)^2
=(1/2a+2/3b-3/4c+1/2a-2/3b-3/4c)(1/2a+2/3b-3/4c-1/2a+2/3b+3/4c)
=(a-2/3c)4/3b
(10)(50又11分之1)^2-(49又11分之10)^2
=(50又1/11+49又10/11)(50又1/11-49又10/11)
=100×2/11
=200/11
(11)(10+100分之1+0.001)^2-(0.01+1000分之1-10)^2
=(10+0.01+0.001)^2-(0.01+0.001-10)^2
=(10+0.01+0.001+0.01+0.001-10)(10+0.01+0.001-0.01-0.001+10)
=0.022×20
=0.44
(1)x^2+x+1/4=(x+1/2)^2
(2)20xy-4x^2-25y^2= -(2x-5y)^2
(3)4(x+y)^2-8(x+y)+4
=4[(x+y)^2-2(x+y)+1]
=4(x+y+1)^2
(4)-4分之1x^2+3分之1xy-9分之1y^2
=-(1/2x+1/3y)^2
(5)(a^2+b^2)^2-...