Question 215448
Ok wow I need some major help!! I need help on how to solve ordered pairs. I looked in my text book and that made me more confused!! 
A) (-9,7), 7x+y<-9 What is the solution of the ordered pair? 
You are asked to determine whether (-9,7) gives you a true statement.
Substitute to get 7*-9+7<-9; -63+7<-9; -56 < -9
That is true.
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B) 2x+9y=21, 
5x-9y=-42
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Add the two equations to get: 
7x = -21
x = -3
Substitute to solve for "y":
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C) 2x+y=5
 3x+4y=-15 
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Multiply thru the 1st equation by 4 to get:
8x+4y = 20
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Subtract the 2nd equation to get:
5x = 35
x = 7
Substitute to solve for "y".
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D) x=8, y=-7
Hummmmm????
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E) Solve by the substitution method: 
9m+n=8, 
m-9n=10 
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m = 9n+10
Substitute for m to solve for "n":
9(9n+10)+n = 8
82n + 90 = 8
82n = -82
n = -1
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Substitute to solve for "m"
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Cheers,
Stan H.