Question 864942: Hi, I need some help with my math homework, its from the lesson (9-5), Multiplication with the addition-or-subtraction method (elimination method), of the algebra structure and method book 1 by mcdougal littell.
The exercise says:
"The point (8,-3) is the intersection of the graphs ax + by = 25 and 3ax - 5by = 3. Find a and b."
PS. Please kindly explain the steps of the procedure so that I understand how to solve the question. Thank you.
Answer by richwmiller(17219)   (Show Source):
You can put this solution on YOUR website! Since we know that (8,-3) is a solution we can substitute 8 for x and -3 for y
ax + by = 25 and 3ax - 5by = 3
8a -3b = 25,
3*8a - 5(-3)b = 3
8a -3b = 25
40a-15b=125 multiply by 5
24a+15b=3
add them
64a-128
a=2
8a -3b = 25
plug in a=2
16-3b=25
-3b=9
b=-3
a=2
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