数学题初一上册目录
1. (-1)+(-2)+(-3)+........+(-50)
=-(1+2+3+……+50)
=-(1+50)*50/2
=-1275
2.(-1)+2+(-3)+4+.......+50
=(2-1)+(4-3)+……(50-49)
=1+1+1+……+1
=25
……1+3=4=2^21+3+5=9=3^2=[(5+1)/2]^21+3+5+7=16=[(7+1)/2]^2……1+3+5+……+2011=[(2011+1)/2]^2=1006^2=1012036
数学题初一上册目录
1. (-1)+(-2)+(-3)+........+(-50)
=-(1+2+3+……+50)
=-(1+50)*50/2
=-1275
2.(-1)+2+(-3)+4+.......+50
=(2-1)+(4-3)+……(50-49)
=1+1+1+……+1
=25
……1+3=4=2^21+3+5=9=3^2=[(5+1)/2]^21+3+5+7=16=[(7+1)/2]^2……1+3+5+……+2011=[(2011+1)/2]^2=1006^2=1012036