计算:(1+111+113+117)×(111+113+117+119)-(1+111+113+117+119)×(111+113+117).
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
答案解析:设x=
+1 11
+1 13
,换元后利用有理数的乘法运算法则进行计算即可得解.1 17
考试点:有理数的乘法.
知识点:本题考查了有理数的乘法,利用换元法求解更简便.