解:(1)
×
×
=
;
(2)(
+
)×
,
=
×
+
×
=
+
,
=
;
(3)
×
×39×55=150;
(4)
×(26×
),
=
×26×
,
=6;
(5)
×
+
×
,
=
+
,
=
;
(6)
×[
-(
+
)],
=
×[
-
-
],
=
×
,
=
;
(7)34-34×
,
=34×(1-
),
=34×
,
=
;
(8)[4-(
-
)]×
,
=[4-
]×
,
=
×
,
=
;
(9)
+
×(2.5-
),
=
+
×(
-
),
=
+
×
,
=
+2,
=2
.
分析:(1)(3)約分計(jì)算;
(2)(4)(7)運(yùn)用乘法分配律簡(jiǎn)算;
(5)此題不能用乘法分配律簡(jiǎn)算,可先算乘法,再算加法;
(6)中括號(hào)內(nèi)運(yùn)用減法的性質(zhì)以及加法交換律與結(jié)合律,最后算括號(hào)外的乘法;
(8)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;
(9)先算括號(hào)內(nèi)的,再算括號(hào)外的乘法,最后算加法.
點(diǎn)評(píng):此題考查了四則混合運(yùn)算,注意運(yùn)算順序和運(yùn)算法則,靈活運(yùn)用所學(xué)的運(yùn)算定律或性質(zhì)進(jìn)行簡(jiǎn)便計(jì)算.