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

1 Answer
May 25, 2016

Answer:

The solution for the system of equations is:
#color(blue)(x = -12/7#

#color(blue)(y = -3/7 #

Explanation:

#color(blue)(y = 2x +3 #..............equation #(1)#
#9y = -3x - 9#....equation #(2)#

Substituting equation #1# in equation #2:#

#9y = -3x - 9#

#9 xx (color(blue)( 2x +3)) = -3x - 9#

#18x + 27 = -3x - 9#

#18x + 3x = - 9 -27#

#21x = -36#

#x = -36/21#

#color(blue)(x = -12/7#

Finding #y# from equation #(1):#
#y = 2x +3 #

#y = 2 xx (-12/7) +3 #

#y = -24/7 +3 #

#y = -24/7 +21/7 #

#color(blue)(y = -3/7 #