分析:算式①⑤根據(jù)四則混合運(yùn)算的運(yùn)算順序計(jì)算即可:先算減法,再算除法與乘法;
算式②可將22.9×7.34變?yōu)?.29×73.4后再根據(jù)乘法分配律計(jì)算;
算式③可根據(jù)一個(gè)數(shù)減兩個(gè)數(shù)的差,等于用這個(gè)數(shù)減去兩個(gè)數(shù)中的被減數(shù)加上減數(shù)的減法性質(zhì)及加法交換律計(jì)算;
算式④可根據(jù)一個(gè)數(shù)減兩個(gè)數(shù)等于減去這兩個(gè)數(shù)的和的減法性質(zhì)及加法交換律計(jì)算.
解答:解:①3451÷17×(323-299)
=3451÷17×24,
=203×24,
=4872;
②22.9×7.34+2.29×26.6
=2.29×73.4+2.29×26.6,
=(73.4+26.6)×2.29,
=100×2.29,
=229;
③
16-(
2-
1)
=
16-
2+
1,
=
16+
1-
2,
=18-
2,
=15
;
④48.48-
23+
31-36.45
=48.48-23.55+31.52-36.45,
=48.48+31.52-(23.55+36.45),
=80-60,
=20.
⑤[1.9-1.9×(
1-1.9)]÷
3=[1.9-1.9×(1.9-1.9)]÷
,
=[1.9-1.9×0]×
,
=1.9×
,
=0.5.
點(diǎn)評(píng):當(dāng)算式中同時(shí)含有分?jǐn)?shù)與小數(shù)時(shí),要根據(jù)式中數(shù)據(jù)的特點(diǎn)靈活將它們互化后再計(jì)算.