2題Maths=] (20分)

1..{ r=2s=24
{ 2s+5r=0

are you sure it is r=2s=24??

2012-11-25 10:58:10 補充：
Question 1
{ r+2s=24...(1)
{ 2s+5r=0...(2)

From (1):
r=24-2s...(3)

Sub (3) into (2)
2s+5(24-2s)=0
2s+120-10s=0
120=8s
s=15

Sub s into (3)
r=24-2(15)
r=-6


For Question 1, I assumed your r=2s=24 means r+2s=24. pls update your question to let me know if this is correct or not :)


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Question 2
{ -13p=9-2q....(1)
{-4q=13+5p.....(2)

From (1):
2q =9+13p
q= (9+13p)/2....(3)

Sub (3) into (2)
-4((9+13p)/2)= 13 + 5p
-2(9+13p)=13+5p
-18-26p=13+5p
-31=31p
p=-1

Sub p into (3)
q=(9+13(-1))/2
q=-2