4. This system of equations has solution (5, -2):
Find the missing values A and B.
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Answer:
Answer is under this sentence
Step-by-step explanation:
(5,-2) is the solution of the equation, which means that x = 5 and y = -2
so you obtain:
5A + 2B = 24
5B - 2A = 31
Now you need to know either A or B. If we know A, we can also know B and vice-versa.
In order to do that, we get rid of either A or B from our equations. So, we multiply the first equation by -5 and the second one by 2. You'll obtain -10B and +10B in those equations:
-25A - 10B = -120
10B - 4A = 62
If we add up both equations, notice how 10B and -10B cancel each other:
-25A - 4A = -120 + 62
-29A = -58
A = 2
Knowing A, we can know B as well. We go back to our initial equations and we choose the 1st one(or the 2nd one):
5A + 2B = 24
5 * 2 + 2B = 24
2B = 24 - 10
2B = 14
B = 7
So A = 2 and B = 7
Note: I suggest you check in case the arithmetics are done correctly.