1. 100^2-99^2+98^2-97^2+……+2^2-1^2=(100-99)*(100+99)+(98-97)*(98+97).....(2-1)(2+1)
=100+99+98.....+2+1=5050
2. (2012-x)^2+(2010-x)^2=(2012-x)^2+(2010-x)^2-2(2012-x)(2010-x)+2(2012-x)(2010-x)
=[(2012-x)-(2010-x)]^2+2(2012-x)(2010-x)=2^2+2*2011=4+4022=4026
3. x^2-x+1\4=0 (x-1/2)^2=0, x=1/2 ,x+1\毕雀2=1
4. (2x-3y)^2-2(2x-3y)(2y-3x)+(3x-2y)^2=.(2x-3y)^2+2(2x-3y)(3x-2y)+(3x-2y)^2
=(2x-3y+3x-2y)^2=(5x-5y)^2=25(1)^2=25
5 . x^2-3x-4=(x+1)^2+m(x+1)+n=x^2+2x+1+mx+m+n =x^2+(2+m)x+(m+n+1)
2+m=-3, m=-5, m+n+1=-4, n=0.
6. (1-1\2^2)(1-1\3^2)(1-1\仔数镇4^2)*……*(1-1\2011^2)=(1+1/2)(1-1/2)(1+1/3)(1-1/3).....
=3/2*1/2*4/3*2/3*3/4*5/4....
对不起,太烦念粗琐了.
记得给我分哦
1002-992+982-972+…+22-12
=(1002-12)-(992-22)+(982-32)-…+(522-492)-(512-502)
=(100+1)(100-1)如备-(99+2)(裤局99-2)+(98+3)(98-3)-…+(52+49)(52-49)-(51+50)(51-50)
=101×99-101×97+101×95-…+101×3-101×1
=101×(99-97+95-…+3-1)
=101×(2+2+…+2)胡橡让
=101×25×2
=5050.
2
548754854
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