(1+3)/1+(3+5)/1+(5+7)/1+(7+9)/1.+(17+19/1+(19+21)/1=?
问题描述:
(1+3)/1+(3+5)/1+(5+7)/1+(7+9)/1.+(17+19/1+(19+21)/1=?
答
等差数列:4+8+12+.+40=220
(1+3)/1+(3+5)/1+(5+7)/1+(7+9)/1.+(17+19/1+(19+21)/1=?
等差数列:4+8+12+.+40=220