SOLUTION: Can you please answer this question? Find a and b so that the line ax+by=9 passes through the points (1,-2) and (4,1)

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Question 815894: Can you please answer this question?
Find a and b so that the line ax+by=9 passes through the points (1,-2) and (4,1)

Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
ax+by=9
(1,-2) and (4,1)
1a-2b=9
4a+b=9
double the second
1a-2b=9
8a+2b=18
add them
9a=27
a=3
3-2b=9
-2b=6
b=-3
ax+by=9
3x-3y=9