How do you solve the system using the elimination method for 3(x-y)=15 and 2x+7=7?

1 Answer
Jul 22, 2015

Answer:

#(x,y) = (0,-5)#
#color(white)("XXXX")#by the elimination method (although the "elimination" has already been done)

Explanation:

Given
[1]#color(white)("XXXX")##3(x-y) = 15#
[2]#color(white)("XXXX")##2x+7 = 7#

Since #y# has already been eliminated in [2]
if we simplify [2] as
[3]#color(white)("XXXX")##2x = 0#
#rArr#
[4]#color(white)("XXXX")##x = 0#

We can then substitute #x=0# back into [1] to get
[5]#color(white)("XXXX")##3(0-y) = 15#
or, after simplification:
[6]#color(white)("XXXX")##y = -5#