题目内容
(2007?清河区)下面各题怎样简便就怎样计算(求未知数X).
5.02-1.37-2.63
×(
+
)+0.8
:X=0.32:4.8
1.25×2.5×32
11÷〔
×(
+
)〕
5.02-1.37-2.63
12 |
5 |
5 |
6 |
1 |
2 |
1 |
5 |
1.25×2.5×32
11÷〔
6 |
11 |
3 |
4 |
1 |
6 |
分析:(1)利用一个数连续减去两个数,等于这个数减去这两个数的和计算:
(2)
×(
+
)利用乘法分配律计算简便,然后利用加法结合律计算;
(3)比例的基本性质“两外项之积等于两内项之积”,把比例转化为0.32x=
×4.8,利用等式的基本性质方程的两边同时除以0.32求解;
(4)把32拆成4×8,利用乘法结合律1.25×8,2.5×4,这样计算简便;
(5)按运算顺序直接计算即可.
(2)
12 |
5 |
5 |
6 |
1 |
2 |
(3)比例的基本性质“两外项之积等于两内项之积”,把比例转化为0.32x=
1 |
5 |
(4)把32拆成4×8,利用乘法结合律1.25×8,2.5×4,这样计算简便;
(5)按运算顺序直接计算即可.
解答:解:(1)5.02-1.37-2.63;
=5.02-(1.37+2.63),
=5.02-4,
=1.02;
(2 )
×(
+
)+0.8,
=
×
+
×
+0.8,
=2+1.2+0.8,
=2+(1.2+0.8),
=2+2,
=4;
(3)
:x=0.32:4.8,
0.32x=0.2×4.8,
0.32x=0.96,
0.32x÷0.32=0.96÷0.32,
x=3;
(4)1.25×2.5×32,
=(1.25×8 )×(2.5×4),
=10×10,
=100;
(5)11÷[
×(
+
)],
=11÷[
×
],
=11÷
;
=22.
=5.02-(1.37+2.63),
=5.02-4,
=1.02;
(2 )
12 |
5 |
5 |
6 |
1 |
2 |
=
12 |
5 |
5 |
6 |
12 |
5 |
1 |
2 |
=2+1.2+0.8,
=2+(1.2+0.8),
=2+2,
=4;
(3)
1 |
5 |
0.32x=0.2×4.8,
0.32x=0.96,
0.32x÷0.32=0.96÷0.32,
x=3;
(4)1.25×2.5×32,
=(1.25×8 )×(2.5×4),
=10×10,
=100;
(5)11÷[
6 |
11 |
3 |
4 |
1 |
6 |
=11÷[
6 |
11 |
11 |
12 |
=11÷
1 |
2 |
=22.
点评:按照四则混合运算的运算顺序来解答,能简算的要间算.
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