求未知数x的值.x-0.8x-6=16 2:5=x:10 13x+56x=23×14 x8=1516.
(1)x-0.8x-6=16,
0.2x-6=16,
0.2x-6+6=16+6,
0.2x=22,
0.2x÷0.2=22÷0.2,
x=110;
(2)2:5=x:10,
5x=2×10,
5x=20,
5x÷5=20÷5,
x=4;
(3)
1 |
3 |
5 |
6 |
2 |
3 |
1 |
4 |
7 |
6 |
2 |
3 |
1 |
4 |
7 |
6 |
7 |
6 |
2 |
3 |
1 |
4 |
7 |
6 |
x=
2 |
3 |
1 |
4 |
6 |
7 |
x=
1 |
7 |
(4)
x |
8 |
15 |
16 |
16x=8×15,
16x=120,
16x÷16=120÷16,
x=7.5.
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