1/2+1+11/2+2+21/2+…+491/2+50.
问题描述:
+1+11 2
+2+21 2
+…+491 2
+50. 1 2
答
+1+11 2
+21 2
+…+491 2
+50,1 2
=(1+2+…+50)×2-50+
×50,1 2
=(1+50)×50÷2×2-50+25,
=2550-50+25,
=2525.