题目内容
(2011?东城区)
736÷16+52 | 220×(0.51-0.31) | 12.5-0.625-
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|
解方程x-
|
解比例21:x=4:
|
分析:(1)先算除法,再算加减;
(2)先计算括号里面的,再计算括号外面的乘法;
(3)利用简便方法先算0.625+
,再算12.5-1;
(4)先算小括号里面的,再算中括号里面的,最后算括号外面的乘法;
(5)先算出x-
x得数,再利用等式的基本性质两边同时除以
求解;
(6)根据比例的基本性质4x=21×
,根据等式的基本性质方程的两边同时除以4求解.
(2)先计算括号里面的,再计算括号外面的乘法;
(3)利用简便方法先算0.625+
3 |
8 |
(4)先算小括号里面的,再算中括号里面的,最后算括号外面的乘法;
(5)先算出x-
1 |
4 |
3 |
4 |
(6)根据比例的基本性质4x=21×
1 |
3 |
解答:解;(1)736÷16+52,
=46+52,
=98;
(2)220×(0.51-0.31),
=220×0.2,
=44;
(3)12.5-0.625-
,
=12.5-(0.625+
),
=12.5-1,
=11.5;
(4)
×[
-(
-
)],
=
×[
-
],
=
×
,
=
;
(5)x-
x=
,
x=
,
x÷
=
÷
,
x=
;
(6)21:x=4:
,
4x=21×
,
4x÷4=7÷4,
x=
.
=46+52,
=98;
(2)220×(0.51-0.31),
=220×0.2,
=44;
(3)12.5-0.625-
3 |
8 |
=12.5-(0.625+
3 |
8 |
=12.5-1,
=11.5;
(4)
2 |
9 |
3 |
4 |
7 |
16 |
1 |
4 |
=
2 |
9 |
3 |
4 |
3 |
16 |
=
2 |
9 |
9 |
16 |
=
1 |
8 |
(5)x-
1 |
4 |
3 |
8 |
3 |
4 |
3 |
8 |
3 |
4 |
3 |
4 |
3 |
8 |
3 |
4 |
x=
1 |
2 |
(6)21:x=4:
1 |
3 |
4x=21×
1 |
3 |
4x÷4=7÷4,
x=
7 |
4 |
点评:此题考查整数、分数、小数、百分数的四则混合运算,能简算要简算;不能简算的,有括号时,要按照先算括号里面的,再算括号外面的;没有括号时,要按照先算乘除法,再算加减法.
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