1/5×8+1/8×11+1/11×14+……+1/92×95等于多少,
问题描述:
1/5×8+1/8×11+1/11×14+……+1/92×95等于多少,
答
1/5×8+1/8×11+1/11×14+……+1/92×95
=1/3x(1/5-1/8+1/8-1/11+1/11-1/14+...+1/92-1/95)
=1/3x(1/5-1/95)
=1/3x18/95
=6/95