中一代數計算方法

1.) 18-3(2r-10) = 2(3r-5)
18 -6r + 30 = 6r – 10
18 + 30 + 10 = 6r + 6r
58 = 12r
12r = 58
6r = 29
r = 29/6

2.) (5d/4)-d =1/2
5d/4 – 4d/4 =1/2
d/4 = ½
d = 4(1/2)
d = 2

3.) e/3 = 2+(e/2)
-2 = e/2 – e/3
-2 = 3e/6 = 2e/6
-2 = e/6
e/6 = -2
e = -2(6)
e = -12

4.) 3=2k/5-(4-k)
3 = 2k/5-4 + k
3 + 4 = 2k/5 + k
7 = 2k/5 + 5k/5
7 = 7k/5
1 = k/5
k = 1(5)
k = 5

5.) y+(3y+2/4)=11
y+3y+2/4=11
y+3y=11- 2/4
4y = 10.5
y = 10.5/4
y = 2.625

6.) 2m/3 = 2m-2+6
2 – 6 = 2m -2m/3
- 4 = 6m/3 – 2m/3
-4 = 4m/3
-1 = m/3
m = -3

7.) 1/5(4+a) =1/4-1/2(1+a)
0.2(4 + a) = 0.25 – 0.5(1 + a)
0.8 + 0.2a = 0.25 -0.5 - 0.5a
0.5a +0.2 a = 0.25 -0.5 – 0.8
0.7a = -1.05
a = -1.05/0.7
a = -1.5

1.) 18-3(2xR-10)=2x(3xR-5)
先計( ) ,( )裹面要先乘除後加減!
2.) 5XD 1
-------- -D= -------
4 2
E題個( )號可免的!
3.) E E
------ = 2+( ---------)
3 2
4.) 3= 2xK除以5再-(4-K)
5.)Y+(3xY+2除以4) =11
6.)2xM除以3= 2xM-2+6
7.) 1除以5x(4+A)= 除以4-除以2x(1-A)


要先乘除後加減呀!

-------------希望幫到你-----------------

好易啫，你將未知數擺埋一齊就計到，例如︰

18-3(2r-10)=2(3r-5)
18-6r+30=6r-10
18+30+10=6r+6r
12r=58
r=58/12