How do you solve the following system?: # 3x+3y= -7 , 4x-y=-27 #

1 Answer
Feb 16, 2016

Answer:

The solution for the system of equations is:

#x= (-88)/15#

# y= 53/15#

Explanation:

#3x+color(blue)(3y)=-7#......equation #1#

#4x-y=-27#, multiplying by #3#
#12x-color(blue)(3y)=-81#.....equation #2#

Solving by elimination

Adding equations #1# and #2#:

#3x+cancelcolor(blue)(3y)=-7#

#12x-cancelcolor(blue)(3y)=-81#

#15x= -88#

#x= (-88)/15#

Finding #y# from equation #1#:
#3x+3y=-7#

#cancel3 xx (-88/cancel15)+3y=-7#

# (-88/5)+3y=-7#
# 3y=-7 + 88/5#

# 3y=-35/5 + 88/5#

# 3y= 53/5#

# y= 53/15#