SOLUTION: The lines 2x + ay + 2b = 0 and ax - y - b = 1 intersect at the point (-1, 3). What is 2a + b?

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Question 351551: The lines 2x + ay + 2b = 0 and ax - y - b = 1 intersect at the point
(-1, 3). What is 2a + b?
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Plug the point into each equation,
2x+%2B+ay+%2B+2b+=+0
2%28-1%29+%2B+a%283%29+%2B+2b+=+0
1.3a%2B2b=2
.
.
.
ax+-+y+-+b+=+1
a%28-1%29-3-b=1
-a-b=1
2.a%2Bb=-1
Multiply eq. 2 by (-1) and add to eq. 1,
3a%2B2b-a-b=2%2B1
highlight%282a%2Bb=3%29