题目内容
(1)(0.34×2400×0.25+3×7
+26.25÷
)÷
;
(2)(
×1
×
)÷(
×
×
);
(3)
+
+
+
+…+
.
3 |
4 |
1 |
3 |
2 |
13 |
(2)(
4 |
7 |
1 |
9 |
4 |
11 |
2 |
11 |
2 |
7 |
5 |
9 |
(3)
1 |
1×4 |
1 |
4×7 |
1 |
7×10 |
1 |
10×13 |
1 |
97×100 |
考点:分数的四则混合运算
专题:运算顺序及法则
分析:(1)根据数字特点,通过数字变形,运用乘法分配律简算.
(2)根据除法的运算性质简算.
(3)通过观察,每个分数的分母中的两个因数相差都是3,因此提出
,然后把每个分数拆成两个分数相减的形式,通过加减相互抵消,解决问题.
(2)根据除法的运算性质简算.
(3)通过观察,每个分数的分母中的两个因数相差都是3,因此提出
1 |
3 |
解答:
解:(1)(0.34×2400×0.25+3×7
+26.25÷
)÷
=(0.34×2400×0.25+3×7
+26.25×3)÷
=[0.34×600×4×0.25+3×(7.75+26.25)]÷
=(0.34×600+3×34)÷
=(34×6+3×34)×
=(3+6)×34×
=9×34×
=1989
(2)(
×1
×
)÷(
×
×
)
=(
÷
)×(
÷
)×(
÷
)
=2×2×2
=8
(3)
+
+
+
+…+
=
×(
+
+
+
+…+
)
=
×(1-
+
-
+
-
+
-
+…+
-
)
=
×(1-
)
=
×
=
3 |
4 |
1 |
3 |
2 |
13 |
=(0.34×2400×0.25+3×7
3 |
4 |
2 |
13 |
=[0.34×600×4×0.25+3×(7.75+26.25)]÷
2 |
13 |
=(0.34×600+3×34)÷
2 |
13 |
=(34×6+3×34)×
13 |
2 |
=(3+6)×34×
13 |
2 |
=9×34×
13 |
2 |
=1989
(2)(
4 |
7 |
1 |
9 |
4 |
11 |
2 |
11 |
2 |
7 |
5 |
9 |
=(
4 |
7 |
2 |
11 |
10 |
9 |
5 |
9 |
4 |
11 |
2 |
11 |
=2×2×2
=8
(3)
1 |
1×4 |
1 |
4×7 |
1 |
7×10 |
1 |
10×13 |
1 |
97×100 |
=
1 |
3 |
3 |
1×4 |
3 |
4×7 |
1 |
7×10 |
3 |
10×13 |
3 |
97×100 |
=
1 |
3 |
1 |
4 |
1 |
4 |
1 |
7 |
1 |
7 |
1 |
10 |
1 |
10 |
1 |
13 |
1 |
97 |
1 |
100 |
=
1 |
3 |
1 |
100 |
=
1 |
3 |
99 |
100 |
=
33 |
100 |
点评:注意观察题目中数字构成的特点和规律,善于灵活运用运算定律或运算技巧,巧妙解答.
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