1+3=(1+3)2/2;1+3+5=(1+5)3;1+3+5+7=(1+7)4/2````,则1+3+5+7+9+```+(2n-1)等于?a nnb (n+1)(n+1)c (1+n)n/2d (n+1)*n/2

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1+3=(1+3)*2/2;1+3+5=(1+5)*3;1+3+5+7=(1+7)*4/2````,则1+3+5+7+9+```+(2n-1)等于?an*nb(n+1)*(n+1)c(1+n)*n/2

1+3=(1+3)*2/2;1+3+5=(1+5)*3;1+3+5+7=(1+7)*4/2````,则1+3+5+7+9+```+(2n-1)等于?a n*nb (n+1)*(n+1)c (1+n)*n/2d (n+1)*n/2
1+3=(1+3)*2/2;1+3+5=(1+5)*3;1+3+5+7=(1+7)*4/2````,则1+3+5+7+9+```+(2n-1)等于?
a n*n
b (n+1)*(n+1)
c (1+n)*n/2
d (n+1)*n/2

1+3=(1+3)*2/2;1+3+5=(1+5)*3;1+3+5+7=(1+7)*4/2````,则1+3+5+7+9+```+(2n-1)等于?a n*nb (n+1)*(n+1)c (1+n)*n/2d (n+1)*n/2
前三个可以看出规律
和=（首项+末项）*项数/2
项数=（末项+1）/2
所以 1+3+5+7+9+```+(2n-1)
=（1+2n-1)*(2n/2)/2
=2n*n/2
=n*n
选a

a
1+3+5+7+9+```+(2n-1)
=（1+2n-1)*(2n/2)/2
=2n*n/2
=n*n

a n*n

1+2+3-4-5+1+1+2+3= 1+3-5*4^2-3= 1 2 3 4 5=1 1()2()3()4()5=1 1+1-2+3-4+5=? 2+3= 5-3= 2-1= 1=5 2=1 5 3=2 1 5 4=3 2 1 5 5=? 计算(+5/2)-(-5/3)=-5/1(-5/2)-(-5/3)=5/12/1-3/1=6/1(-2/1)-3/1=-6/1 -5X-2/1=3/1(X-3/1) 3+1/2+1/3+1/4+5=? 求和Sn=1*(1/3)+3*(1/3)^2+5*(1/3)^3+.+(2n-1)*(1/3)^n求和Sn=1*(1/3) + 3*(1/3)^2 + 5*(1/3)^3 +.+(2n-1)*(1/3)^n 1+2=3 4+5=? (1).3x+5/2=2x-1/3 1+3/2=5/2对吗 1+2=3? D=3 1 -1 2-5 1 3 -42 0 1 -11 -5 3 -3 2/3+3/4x=1 5/8x+2/3×1/2=1 1+1=?还有1+2+3+4+5=?