解:(1)
×
×
,
=
;
(2)
÷
×
,
=
×
×
,
=
;
(3)5-
÷
-
,
=5-
×
-
,
=5-
-
,
=5-(
+
),
=5-2,
=3;
(4)
×
+
,
=
×
+
×
,
=
×
×2,
=
;
(5)
×[0.5÷(
×
)],
=
×[
÷
],
=
×[
×
],
=
×
,
=
;
(6)
×
×
,
=
;
(7)
÷
,
=
×
×
,
=
;
(8)(0.75-
)×(
+
),
=(
-
)×
,
=
×
,
=
.
分析:(1)約分計(jì)算;
(2)把除法改為乘法,通過(guò)約分即可;
(3)先算除法,然后運(yùn)用減法的性質(zhì)簡(jiǎn)算;
(4)把除法改為乘法,加號(hào)兩邊的算式相同,用一個(gè)乘2即可;
(5)把0.5改為
,先算小括號(hào)內(nèi)的,再算中括號(hào)內(nèi)的,最后算括號(hào)外的;
(6)與第(1)題相同;
(7)把除法改為乘法,約分計(jì)算;
(8)把小數(shù)化為分?jǐn)?shù),兩個(gè)括號(hào)同時(shí)計(jì)算.
點(diǎn)評(píng):此題主要考查分?jǐn)?shù)、小數(shù)的四則混合運(yùn)算的運(yùn)算順序和應(yīng)用運(yùn)算定律進(jìn)行簡(jiǎn)便計(jì)算的能力.