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[數學]d.e.

發表 zachary 於 星期三 五月 24, 2006 5:44 pm

#ed_op#DIV#ed_cl#有兩題d.e.唔知點解...#ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#1.x#ed_op#SUP#ed_cl#2#ed_op#/SUP#ed_cl#u"+xu'+u=(x#ed_op#SUP#ed_cl#2#ed_op#/SUP#ed_cl#-x+1)e#ed_op#SUP#ed_cl#-x#ed_op#/SUP#ed_cl##ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#2.y"-4y'+x#ed_op#SUP#ed_cl#2#ed_op#/SUP#ed_cl#(y'-4y)=2xe^(-x#ed_op#SUP#ed_cl#3#ed_op#/SUP#ed_cl#/3)#ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl# #ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#第一題我解到C.F.=c#ed_op#SUB#ed_cl#1#ed_op#/SUB#ed_cl#cos(Lnx)+c#ed_op#SUB#ed_cl#2#ed_op#/SUB#ed_cl#sin(Lnx)...#ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#particular integral有個明顯的解u#ed_op#SUB#ed_cl#p#ed_op#/SUB#ed_cl#=e#ed_op#SUP#ed_cl#-x#ed_op#/SUP#ed_cl#...但唔知係唔係咁簡單......#ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl# #ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#第二題是知道一定有個解是y#ed_op#SUB#ed_cl#c#ed_op#/SUB#ed_cl#=c#ed_op#SUB#ed_cl#1#ed_op#/SUB#ed_cl#e#ed_op#SUP#ed_cl#4x#ed_op#/SUP#ed_cl#......#ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl# #ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl#請各位幫幫忙...#ed_op#/DIV#ed_cl#