1x2+2x3+3x4+4x5...+15x16,结果是奇数还是偶数?
1x2+2x3+3x4+4x5+……+199x200的和是奇数还是偶数?
求齐次线性方程组x1+2x2+x3+x4+x5=1 2x1+4x2+3x3+x4+x5=2 -x1-2x2+x3+3x4
1分解因式:2x4-x3-13x2-15=?2.分解因式:x5+x4+x3+x2+x+1=?3分解因式:x4-4x2+6
解方程组X2+X3+X4=1 X1+X2+X3=5 X3+X4+X5=-5 X4+X5+X1=-3 X5+X1+X2=2
一道简便计算数学题1X2+2X3+3X4+4X5...+n(n+1)一1X2+2X3+3X4+4X5...+2013X2
已知数据x1,x2,x3,x4,x5的平均数是20,那么另一组数据x1,x2+1,x3+2,X4+3,X5+4的平均数
已知数据X1,X2,X3,X4,X5的平均数是X拔,则一组新数据X1+1,X2+2,X3+3,X4+4,X5+5的平均数
简算.1/1X2+1/2X3+1/3X4+1/4X5+.+1/199X200,
1/1x2+1/2x3+1/3x4+1/4x5+```````+1/2008x2009=?
1x2/1+2x3/1+3x4/1+4x5/1+…+39x40/1
1/1x2+1/2x3+1/3x4+1/4x5.1/2005x2006=?
1/1x2+1/2x3+1/3x4+1/4x5.1/9x10简算