计算:(1+1/11+1/13+1/17)×(1/11+1/13+1/17+1/19)-(1+1/11+1/13+1/17+1/19)×(1/11+1/13+1/17).
问题描述:
计算:(1+
+1 11
+1 13
)×(1 17
+1 11
+1 13
+1 17
)-(1+1 19
+1 11
+1 13
+1 17
)×(1 19
+1 11
+1 13
). 1 17
答
设x=
+1 11
+1 13
,1 17
则原式=(1+x)×(x+
)-(1+x+1 19
)x,1 19
=x+
+x2+1 19
x-x-x2-1 19
x,1 19
=
.1 19