2025年同步练习册山东五年级数学上册青岛版第141页答案
(3)脱式计算,能简算的要简算。
0.25×6.82×4
=0.25×4×6.82=1×6.82=6.82
1.3+1.64÷4
=1.3+0.41=1.71

12.68-4.8-3.68
=12.68-3.68-4.8=9-4.8=4.2
3.6÷1.2-0.8×2.7
=3-2.16=0.84

答案

0.25×6.82×4
=0.25×4×6.82
=1×6.82
=6.82
1.3+1.64÷4
=1.3+0.41
=1.71
12.68-4.8-3.68
=12.68-3.68-4.8
=9-4.8
=4.2
3.6÷1.2-0.8×2.7
=3-2.16
=0.84
(4)解方程。
2.1+4x= 8.5 3x+2x= 2.5
12(x+3.7)= 144 5x-3×11= 42
2.1+4x=8.5
解：4x=8.5-2.1
4x=6.4
x=6.4÷4
x=1.6
3x+2x=2.5
解：5x=2.5
x=2.5÷5
x=0.5
12(x+3.7)=144
解：x+3.7=144÷12
x+3.7=12
x=12-3.7
x=8.3
5x-3×11=42
解：5x-33=42
5x=42+33
5x=75
x=75÷5
x=15

答案

2.1+4x=8.5
解：4x=8.5-2.1
4x=6.4
x=6.4÷4
x=1.6
3x+2x=2.5
解：5x=2.5
x=2.5÷5
x=0.5
12(x+3.7)=144
解：x+3.7=144÷12
x+3.7=12
x=12-3.7
x=8.3
5x-3×11=42
解：5x-33=42
5x=42+33
5x=75
x=75÷5
x=15