计算:1/2+(1/3+2/3)+(1/4+2/4+3/4)+…+(1/99+2/99+…+97/99+98/99)
问题描述:
计算:
+(1 2
+1 3
)+(2 3
+1 4
+2 4
)+…+(3 4
+1 99
+…+2 99
+97 99
) 98 99
答
原式=
+1+11 2
+…+491 2
=(
+49)×98÷21 2
=2425
.1 2