题目内容
计算或解方程
①13÷19+18×
②4.25+3
-1
+
-2
③
x=2+2x.
①13÷19+18×
13 |
19 |
②4.25+3
3 |
7 |
1 |
4 |
11 |
7 |
③
7 |
2 |
分析:分数的四则混合运算同整数的四则混合运算一致,先算乘除,后算加减,有括号的先算括号内的.分数的分母相同的分数结合起来可使运算简化.
解答:解:①13÷19+18×
,
=
+18×
,
=
×(1+18),
=13;
②4.25+3
- 1
+
-2,
=4.25-2+(3
+
)-1
,
=2.25+5-1
,
=2
-1
+5,
=1+5,
=6;
③
x=2+2x,
(
-2)x=2,
x=2,
x=
.
13 |
19 |
=
13 |
19 |
13 |
19 |
=
13 |
19 |
=13;
②4.25+3
3 |
7 |
1 |
4 |
11 |
7 |
=4.25-2+(3
3 |
7 |
11 |
7 |
1 |
4 |
=2.25+5-1
1 |
4 |
=2
1 |
4 |
1 |
4 |
=1+5,
=6;
③
7 |
2 |
(
7 |
2 |
3 |
2 |
x=
4 |
3 |
点评:此题考查了分数的四则混合运算和方程的解和解方程.
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