递等式两道; 7x8.5+(3.5+1/4x10)除以5 101x1/5-1/5x2
递等式两道; 7x8.5+(3.5+1/4x10)除以5 101x1/5-1/5x2
1x2+2x4+3x6+4x8+5x10+.+20x40 怎么算?
1x2+2x4+3x6+4x8+5x10+.+20x40 简便计算
计算:1/1x2+1/2x3+1/3x4+1/4x5+1/5x6+1/6x7+1/7x8+1/8x9+1/9x10.
2x2/1x3+4x4/3x5+6x6/5x7+8x8/7x9+10x10/9x11+12x12/11x13 仔细看看
样本x1,x2...x10的平均数为5,方差为7,则3x1-1,3x2-1...3x10-1的平均数、方差分别是多少?
11.2x8.1+5/4+53.7x1.9 简算
已知:x1=1/2+1/3,x2=1/3+1/4,x3=x2+x1,x4=x3+x2.,x10=x9+x8,求:x7/x
41.2X8.1+1.1X12.5+53.7X1.9
(1)若x1,x2...x10的方差为3,求数据x1+2,x2+2...x10+2的方差(2)2,3,5,4,x的平均数
5/4x23.3+4/5x6又7/10 简算 11.2x8.1+5/4+53.7x1.9 简算
2x3十4x6十6x9十8x12十10x15分之1x2十2x4十3x6十4x8十5x10.