How do you solve the following system?: #2x -9y =-3 , -x +y = 8#

1 Answer
Alan P.
Nov 26, 2015

#x=-69/7#; #y=-13/7#

Explanation:

Given
[1]#color(white)("XXX")2x-9y=-3#
[2]#color(white)("XXX")-x+y=8#

[2]# xx 9 rarr#
#color(white)("XXX")#[3]#color(white)("XXX")-9x+9y=72#

[1]# + # [3] #rarr#
#color(white)("XXX")#[4]#color(white)("XXX")-7x=69#

[4] #div (-7) rarr#
#color(white)("XXX")#[5]#color(white)("XXX")x=-69/7#

[2]# xx 2 rarr#
#color(white)("XXX")#[6]#color(white)("XXX")-2x+2y=16#

[1]# + # [6]# rarr#
#color(white)("XXX")#[7]#color(white)("XXX")-7y = 13#

[7] #div (-7) rarr#
#color(white)("XXX")#[8]#color(white)("XXX")y=-13/7#

Related questions
See all questions in Systems Using Substitution
Impact of this question
1238 views around the world
You can reuse this answer
Creative Commons License