tangpakchiu 寫到:#ed_op#DIV#ed_cl##ed_op#SPAN lang=EN-US#ed_cl##ed_op#O:P#ed_cl##ed_op#SPAN lang=EN-US#ed_cl##ed_op#SPAN style="FONT-FAMILY: 文鼎中仿"#ed_cl##ed_op#BR#ed_cl#設x+y+z+u=12#ed_op#/SPAN#ed_cl##ed_op#SPAN lang=EN-US#ed_cl#,#ed_op#/SPAN#ed_cl##ed_op#SPAN style="FONT-FAMILY: 文鼎中仿"#ed_cl#求#ed_op#/SPAN#ed_cl##ed_op#SPAN lang=EN-US#ed_cl# #ed_op#I#ed_cl#x#ed_op#/I#ed_cl# , #ed_op#I#ed_cl#y#ed_op#/I#ed_cl##ed_op#/SPAN#ed_cl##ed_op#SPAN style="FONT-FAMILY: 文鼎中仿"#ed_cl#為正奇數#ed_op#/SPAN#ed_cl##ed_op#I#ed_cl##ed_op#SPAN lang=EN-US#ed_cl#z#ed_op#/SPAN#ed_cl##ed_op#/I#ed_cl##ed_op#SPAN lang=EN-US#ed_cl# , #ed_op#I#ed_cl#u#ed_op#/I#ed_cl##ed_op#/SPAN#ed_cl##ed_op#SPAN style="FONT-FAMILY: 文鼎中仿"#ed_cl#為正偶數之解有#ed_op#/SPAN#ed_cl##ed_op#SPAN lang=EN-US#ed_cl#__________#ed_op#/SPAN#ed_cl##ed_op#SPAN style="FONT-FAMILY: 文鼎中仿"#ed_cl#組#ed_op#/SPAN#ed_cl##ed_op#SPAN lang=EN-US#ed_cl#.#ed_op#/SPAN#ed_cl##ed_op#/SPAN#ed_cl##ed_op#/O:P#ed_cl##ed_op#/SPAN#ed_cl##ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl##ed_op#BR#ed_cl##ed_op#/DIV#ed_cl#
#ed_op#BR#ed_cl#x+y = 2至8, z+u = 4至10, 組合有四種 {2+10, 4+8, 6+6, 8+4};#ed_op#BR#ed_cl#x,y,z,u在這段數段中皆有四個不同數字可選 [ x,y : (1,3,5,7); z,u : (2,4,6,8)];#ed_op#BR#ed_cl#Σ#ed_op#SUP#ed_cl#4#ed_op#/SUP#ed_cl##ed_op#SUB#ed_cl#i=1#ed_op#/SUB#ed_cl# [i*(4-i)] = C#ed_op#SUP#ed_cl#4-1+3#ed_op#/SUP#ed_cl##ed_op#SUB#ed_cl#4-1#ed_op#/SUB#ed_cl# = 20組#ed_op#BR#ed_cl##ed_op#DIV#ed_cl##ed_op#/DIV#ed_cl#