Question

2.5x+2.1(3-x)=7.1

一次一元方程,
1）2(x-0.7)-3(1.4-2x)=0 (2)7(2x-1)-3(4x-1)=5(3x+2)-1 (3)x/2- 5x+2/6 =1-2x-4/3 (4)-2(3x-7)=x+13 (5)x-2/3+3x+4/6=1/2 (6)2/5x-8=1/4-0.2x (7)1-x-7/3=4(x-10) (8)y+1/6=y/3+1 (9)3/4[4/3(1/2x-1)-8]=3/2+x (10）2x-1/6 - 3x-1/8=1 (11)2x-1/3 - 10x+1/6=2x+1/4-1 (12)4(x+2)/3-x-7/5=12
就3步光写去分母,移项,系数化为一就行了

Answer 1

1）
2（x-0.7)-3(1.4-2x)=0
2x-2*0.7-3*1.4+3*2x=0
2x-1.4-4.2+6x=0
8x=0+1.4+4.2
x=5.6/8
x=0.7
2
7(2x-1)-3(4x-1)=5(3x+2)-1
14x-7-12x+3=15x+10-1
14x-12x-15x=10-1+7-3
-13x=13
x=-1
3
x/2-5x+2/6=1-2x-4/3
x/2-5x+2x=1-4/3-2/6
x-10x+4x=2-8/3-2/3
-5x=-4/3
x=4/15
4
-2(3x-7)=x+13
-6x+14=x+13
-6x-x=13-14
-7x=-1
x=1/7
5
x-2/3+3x+4/6=1/2
4x=1/2+2/3-2/3
4x=1/2
x=1/8
6
2/5x-8=1/4-0.2x
0.4x+0.2x=0.25+8
0.6x=8.25
x=13.75
7
1-x-7/3=4(x-10)
1-x-7/3=4x-40
-x-4x=-40-1+7
-5x=-34
x=6.8
8
y+1/6=y/3+1
3y+0.5=y+3
3y-y=3-0.5
2y=2.5
y=1.25
9
3/4[4/3(1/2x-1)-8]=3/2+x
3/4[2/3x-4/3-8]=3/2+x
1/2x-1-6=3/2+x
1/2x-x=3/2+1+6
-1.5x=8.5
x=-17/3
10
2x-1/6-3x-1/8=1
-x=1+1/6+1/8
-x=31/24
x=-31/24
11
2x-1/3-10x+1/6=2x+1/4-1
2x-10x-2x=1/4-1+1/3-1/6
-10x=-7/12
x=7/120
12
4(x+2)/3-x-7/5=12
4(x+2)-3x-21/5=36
4x+8-3x-4.2=36
x=36-8+4.2
x=32.2
终于写完了～累ing