解方程和比例. ①4x+3×0.7=6.5 ②x:8=3/4:11/5 ③2x+2×0.7=4.5 ④x:8=1/4:1/5.
问题描述:
解方程和比例.
①4x+3×0.7=6.5 | ②x:8=
|
③2x+2×0.7=4.5 | ④x:8=
|
答
①4x+3×0.7=6.5,
4x+2.1-2.1=6.5-2.1,
4x=4.4,
4x÷4=4.4÷4,
x=1.1;
②x:8=
:13 4
,1 5
1
x=8×1 5
,3 4
1
x÷11 5
=6÷11 5
,1 5
x=5;
③2x+2×0.7=4.5,
2x+1.4-1.4=4.5-1.4,
2x=3.1,
2x÷2=3.1÷2,
x=1.55;
④x:8=
:1 4
,1 5
x=8×1 5
,1 4
x÷1 5
=2÷1 5
,1 5
x=10.