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

 May 1, 2021
 #1
avatar+121000 
+1

Note  that  the second equation can be arranged as

 

y =  6x  -  42

 

Sub this into  the first equation for  y

 

2x - 9 ( 6x - 42)  =  14       simplify

 

2x  - 54x  + 378  =  14

 

-52x  =  14  - 378

 

-52x  = -364

 

x  = -364 / -52    =   7

 

And   y   =  6(7) - 42  =  0

 

So....xy  =  7*0  =  0

 

cool cool cool

 May 1, 2021
 #2
avatar+731 
+1

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

 

2x - 9y = 14 (1)

6x = 42 + y (2)

(1) × 3 = 6x - 27y = 42 (3)

(2) & (3) = 42 + y - 27y = 42

y = 27y

Only holds if y = 0 assuming y is a real number.

If x is also a real number, x * y will always be 0 because y = 0.

 

xy=0

 

laugh


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