Question 1025468
<pre>
5x + 2y = 4 
3x + 4y + 2z = 6 
7x + 3y + 4z = 29


A.	
3x + 4y + 2z = 6  &#8594;     3x + 4y + 4z = 6 
<font color="red"><b>Oh,oh! They forgot to multiply the 6 by 2></font></b>
7x + 3y + 4z = 29 &#8594; (­-)7x + 3y + 4z = 29

-4x ­-  y  =- ­23

B.	
3x + 4y + 2z = 6 &#8594;     6x + 8y + 4z = 12 
 7x + 3y + 4z = 29 &#8594; (-­)7x + 3y + 4z = 29

-x + 5y  = ­-17

C.	
3x + 4y + 2z = 6 &#8594;     6x + 8y + 4z =  6
<font color="red"><b>Oh,oh! They forgot to multiply the 6 by 2></font></b>
7x + 3y + 4z = 29 &#8594; (-­)7x + 3y + 4z = 2

-x + 5y =- ­23

D.	
3x + 4y + 2z = 6 &#8594;     6x + 8y + 4z = 12 
7x + 3y + 4z = 29 &#8594; (-­)7x + 3y + 4z = 29

-x + 8y = 41
<font color="red"><b>Oh,oh! They didn't subtract 3y from 8y,
and also they added 29 to 12 when they should 
have subtracted.></font></b>

Edwin</pre>