| 用递等式计算. ①7.2÷1.6+0.45 | ②(1- )÷ ÷3 |
③29- × ÷![]() | ④ ÷[ -( + )]. |
=4.5+0.45,
=4.95;
(2)(1-
)÷
÷3,=

÷3,=
;(3)29-
×
÷
,=29-
,=29-2,
=27;
(4)
÷[
-(
+
)],=
÷[
-
]. =
,=
.分析:(1)先算除法,再算加法,
(2)先算括号里面的,再算除法,
(3)先把除法转化成乘法,再算乘法,最后算减法,
(4)先算小括号里面的,再算中括号里面的,最后算除法.据此解答.
点评:本题综合考查了学生四则运算的计算能力,注意要细心.