1,2,4,7,11,16.n n等于几
1,2,4,7,11,16.n n等于几
1+3+7+9+…+(2n-1)+(2n+1)+(2n+3)等于几
Sn=n(n+2)(n+4)的分项等于1/6[n(n+2)(n+4)(n+5)-(n-1)n(n+2)(n+4)]吗?
1乘2+2乘3+3乘4+.n(n+1)等于几分之几n(n+1)(n+2)
1+3+5+7+9+……+(2n-1)+(2n+1)+(2n+3)等于几?
n(n+1)(n+2)等于多少?
1+2+3+4+5+6+7+8+9+.n 等于几?
n-m等于-3则4-2m+2n等于几
+(n-1)!+(n-2)!+.+(n-n)!等于什么?
(-2)的2n次方等于?(-2)的2n-1次方等于几?(其中n为正整数)
已知m:n=4:1,当m=12时,n=等于几?,当m十n=20时,n=等于几?
n乘(n加1)分之1等于几