x,y,10,11,9,平均数10,方差2,求绝对值_数学解答

x,y,10,11,9,平均数10,方差2,求绝对值

人气：456 ℃　时间：2019-10-19 08:22:31

解答

(x+y+10+11+9)/5=10x+y+30=50x+y=20 (1)(x-10)^2+(y-10)^2+(10-10)^2+(11-10)^2+(9-10)^2=2*5(x-10)^2+(y-10)^2+0+1+1=10(x-10)^2+(y-10)^2=8x^2-20x+100+y^2-20y+100=8x^2-20x+y^2-20y=-192 (2)(2)+20*(1):x^2+y^2=...