How do you solve #x + y + 3# and #2x + 3y = 9#?

1 Answer
Sep 5, 2015

Answer:

The solution is
#color(blue)(x=-18, y=15#

Explanation:

Solving assuming that the first equation : #x+y+3=0#

#x+y=-3#, multiplying this equation by 2:
#color(blue)(2x)+2y=-6#......equation #1#

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

Solving by elimination.

Subtracting equation #2# from #1# eliminates #color(blue)(2x#

#cancelcolor(blue)(2x)+2y=-6#
#-cancelcolor(blue)(2x)-3y=-9#

#-y=-15#
#color(blue)(y=15#

Finding #x# by substituting the value of #y# in equation #1#
#x+y=-3#
#x=-3-y#
#x=-3-15#
#color(blue)(x=-18#