two maths questions(f.2)

Q.33

t = mn/(m + n)

mn = t(m + n)

mn = tm + tn

mn - tm = tn

m(n - t) = tn

m = tn/(n - t)

2010-12-28 23:19:05 補充：
Q.29 唔知想問乜。

2010-12-30 00:23:36 補充：
Q.29

s = a(rⁿ - 1)/(r - 1)

When a = 32, r = 1/2 and n = 3:

s = 32[(1/2)³ - 1] / [(1/2) - 1]

s = 32[(1/8) - 1] / (-1/2)

s = -64 x (-7/8)

s = 56 ...... (Ans)