急需求數學題目!!!要過程!!!拜託!!!

As follow AS~~~~

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1. 2/x - 3 + 1 / x -6
= 1/x + 2/x -9
= 1 + 2 / x - 9
= 3/x-9

2. 5p - 7 = 3(p+q)
5p - 7 = 3p + 3q
5p - 3p = 3q + 7
2p = 3q + 7
p = ( 3q + 7 ) / 2

3. y = (x-2) / (x+1)
y (x+1) = x -2
yx + y = x - 2
yx - x = -y -2
x (y-1) = - (y+2)
x = -(y+2) / (y-1)

4. s = (2+r) / (r-7)
s (r-7) = 2+r
sr - 7s = 2+r
sr - r = 7s + 2
r(s-1) = 7s + 2
r = (7s+2) / (s-1)

5. y = a+ ( b/2x)
y = 2xa/2x + b/2x
y = (2xa + b) / 2x
2xy = 2xa + b
2xy - 2xa = b
x(2y-2a) = b
x = b / (2y-2a)