math f.1

a)We can use a equation to solve this problem.

The equation:
1-2a-18=5a 4
-2a-5a=4-1 18
-7a=21
-7a/-7=21/-7
a=-3

P(-11,3),Q(7,3),they have the same y-coordinate,so they have the same height.
We just calculate the x-coordinate.

b)Let M be the point between P and Q .The distance in a half of PQ is 9.
So,the coordinate of M is:
=（-11 9，3） or ( 7-9,3）
=(-2,3)



I hope I can help you!!^_^

2008-05-11 17:58:19 補充：
~Annie~*'s answer must be wrong!It is because the answer must not be a fraction!She have made a calculation mistake!You can try my answer,and check it wether the answer is right or wrong.

To和事碧:
你唔識,就冇答,不如索性唔好答整題.
畀啲机会人吔la!!!

a)5a+4-1-2a=18
2a=15
a=7.5
SOR...我淨係識a
b我唔識
我coordiante不太好的說...