How do solve the following linear system?: # y = 4x + 4, 3x - y = -6 #?

1 Answer
May 21, 2018

Answer:

#x=2# and #y=12#

Explanation:

In two linear equation system, make one variable the subject and substitute that variable in the second equation.

#y = 4x+4# #-># equation 1
#3x-y=-6# #-># equation 2

Substitute #y# from equation 1 to equation 2:

#3x - (4x+4) = -6#

#3x-4x-4 = -6#

#-x-4 = -6#

#-x = -6+4#

#-x = -2#

#x = 2#

Substitute #x=2# in equation 1 or equation 2 to get value of #y#.
Lets take equation 1:

#y=4x+4# #-># equation 1

#y=4(2) + 4#

#y=8+4#

#y=12#

So we get #x=2# and #y=12#

Check the answer:

#3x-y=-6#
#3(2) - 12 = -6#
#6-12=-6#
#-6=-6# #-># Correct