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| Question 908138:  3x-5y+z=10
 2x+2y-z=12
 5x+3y-2z=15
 Answer by mananth(16946)
      (Show Source): 
You can put this solution on YOUR website! 3      	x	+	-5      	y	+	      	z	=	10      			--------------				1 2      	x	+	2      	y		-      	z	=	12      			--------------				2
 5      	x	+	3      	y	+	-2      	z	=	15      			--------------				3
 
 consider equation 1 &2				Eliminate	y
 Multiply 1 by		2      					-5
 Multiply 2 by		5      					4
 we get
 6      	x		+	-10      	y	+	2      	z	=	20
 10      	x		+	10      	y	+	-5      	z	=	60
 Add the two
 16      	x		+	0      	y	+	-3      	z	=	80	-------------				4
 consider equation 2 & 3				Eliminate	y
 Multiply 2 by				3
 Multiply 3 by				2
 we get
 6      	x	+	6      	y	+	-3      	z	=	36
 10      	x	+	6      	y	+	-4      	z	=	30
 Add the two
 16      	x	+	12      	y	+	-7      	z	=	66      	-------------5				5
 Consider (4) & (5)			Eliminate	x
 Multiply 4 by				1
 Multiply (5) by				-1
 we get
 16      	x	+	-3      	z	=	80
 -16      	x	+	7      	z	=	-66
 Add the two
 4      	z	=	14
 /	4
 z	=	3  1/ 2
 16      	x		-7      	z=	66
 16      	x		-24  1/ 2	=	66
 x	=	5 21/32
 Plug x & z in eq (1)
 3x-5y	+z=10	--------------1
 16 31/32-5y	+	3  1/ 2		=	10
 -5y=	-10 15/32
 y	=2  3/32
 x=	5 21/32	y=	2  3/32	z=	3  1/ 2
 
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