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I can not figure this out :(
A.)
3a + 4b = -3
5a - 4b = -6
? = ?
(and I put the second answer as -9/8, it was marked wrong?)
B.)
x - 4y = 15
-x - y = -11
? = ? (and for this one I put 0=4 = 0 and it was also marked wrong)
can someone help me out? where do i do wrong in these two problems? what are the correct answers and steps to solve them? thanks!
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Want to answer more questions in the Miscellaneous category?
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Nobody should really be giving you the answers, because that would be academic dishonesty. That said, we can definitely help you get the right start!
Using question A as an example, it's a simple matter of looking to see what the two equations have in common.
There's a +4b in the first, and a -4b in the second, right? So we rearrange the equations to isolate those.
4b = -3 - 3a
4b = 6 + 5a
Now, those two are equivalent, because 4b = 4b.
-3 - 3a = 6 + 5a
8 a = -9
As you correctly discovered, a = -9/8. Where did you go wrong? Well, there were two variables, were there not? You have to use your value for a to find b by plugging it into one of the original equations.
3(-9/8) + 4b = -3
Now you can solve!
As for the second one, I'm really not sure how you got the answer you did. Try isolating x, because it's the easiest one. Use the same procedure as above, and you should have no problems.
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