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If 2x - 9y = 14 and 6x=42+y-2x, what is the value of the product xy?

 Apr 12, 2022
 #1
avatar+124592 
+1

We can write   these two equations

 

2x - 9y   = 14     (1)

8x - 42  = y        (2)

 

Sub (2)  into (1)

 

2x - 9(8x - 42)  = 14

2x - 72x + 378  = 14

-70x  = 14 - 378

-70x = -364

x = -364 / -70  =  26/5 =  5.2

 

y = 8 (5.2) -42  =  -0.4

 

xy  =  (5.2) (-0.4)   =  -2.08

 

cool cool cool

 Apr 12, 2022
 #2
avatar+114 
-3

No not that

 Apr 12, 2022
 #3
avatar+2432 
+1

No, C Phill's answer is correct. 

 

By graphing the system, we find that the solution for the system is (5.2, -0.4), and \(5.2 \times -0.4 = \color{brown}\boxed{-2.08}\)

 

 Apr 12, 2022
 #4
avatar+124592 
0

THX for confirming my answer, BuilderBoi  !!!!

 

cool cool cool

CPhill  Apr 12, 2022

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