(8/15÷0.32−7/9×0.375)÷13/8 (0.5+0.25+0.125)÷(0.5+0.25+0.125) 139×137/138+137×11/138 1-3+5-7+…-99+101.
问题描述:
(
÷0.32−8 15
×0.375)÷17 9
3 8
(0.5+0.25+0.125)÷(0.5+0.25+0.125)
139×
+137×1137 138
1 138
1-3+5-7+…-99+101.
答
(1)(
÷0.32-8 15
×0.375)÷17 9
3 8
=(
÷8 15
-8 25
×7 9
)÷13 8
3 8
=(
×8 15
-25 8
×7 9
)÷13 8
3 8
=(
-5 3
)×7 24
8 11
=
×33 24
8 11
=1;
(2)(0.5+0.25+0.125)÷(0.5+0.25+0.125)=1;
(3)139×
+137×1137 138
1 138
=137×
+137×139 138
139 138
=137×
×2139 138
=
;19043 69
(4)1-3+5-7+…-99+101
=1+(5-3)+(9-7)+(13-11)+…+(101-99)
=1+2×25
=51.