问题
解答题
计算下面各题能简算的要简算. ①(
②
③
④3-
|
答案
①(
-6 7
)÷5 6 1 42
=(
-6 7
)×425 6
=
×42-6 7
×425 6
=36-35
=1;
②
×3+7 10
÷3 10 1 3
=
×3+7 10
×33 10
=(
+7 10
)×33 10
=1×3
=3;
③
+5 8
+3 7
+3 8 4 7
=(
+5 8
)+(3 8
+3 7
)4 7
=1+1
=2;
④3-
×3 2
-10 21
.2 7
=3-
-5 7 2 7
=3-(
+5 7
)2 7
=3-1
=2.