观察下式:1=1、2+3+4=3、3+4+5+6+7=5、
4+5+6+7+8+9+10=7、…则第几个式子是 ( )
A.n+(n+1)+(n+2)+…+(2n-1)= n |
B.n+(n+1)+(n+2)+…+(2n-1)= (2n-1) |
C.n+(n+1)+(n+2)+…+(3n-2) = (2n-1) |
D.n+(n+1)+(n+2)+…+(3n-1) = (2n-1) |
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观察下式:1=1、2+3+4=3、3+4+5+6+7=5、
4+5+6+7+8+9+10=7、…则第几个式子是 ( )
A.n+(n+1)+(n+2)+…+(2n-1)= n |
B.n+(n+1)+(n+2)+…+(2n-1)= (2n-1) |
C.n+(n+1)+(n+2)+…+(3n-2) = (2n-1) |
D.n+(n+1)+(n+2)+…+(3n-1) = (2n-1) |