F.1數學問題 help~~(15點)

1. (7u - 4u -1)/2 = 21
(3u-1)/2 =21
3u-1 =42
3u=43
u=43/3
2. (t+13)/5 = 1/5 - (t+5)/2
2(t+13) = 2 - 5(t+5)
2t+26 = 2-5t - 25
2t + 26 = -5t -23
7t + 49=0
7t = -49
t = -7

1. 7u - 4u-12 =41/10
3u-12=41/10
3u-12+1=41/10+1
3u22=5 1/102
3u/3=10 1/53
u=3 2/5
∴這條方程的解(答案)是3 2/5

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7u-(4u-1)/2 =21
7u- (4u/2)-(-1/2)=21
7u- 2u +1/2 =21
5u = 21-1/2
5u= 20.5
u= 20.5/5
u= 4.1 OR 41/10.....

1. 7u - 4u-1/2 =21
7u - 4u-1/2 =21
3u-1/2=21
3u=21+1/2 (即21又2分之1)
u= 21 1/2 除以3
u=2分之43 乘以 3分之1
u=6分之43
u=7 1/6 (即7又6分之1)


2. t+13除以5 =1除以5 - t+5除以2
t+2.6=0.2-t+2.5
t+t=0.2+2.5-2.6
2t=0.1
t=0.1除以2
t=0.05

1)7u - (4u - 1) / 2 = 21

14u - (4u - 1) = 42

14u - 4u + 1 = 42

10u = 41

u = 41/10