What method would you use for this system of linear equations? why?

x= 2y-7
y - 3x = -9

1 Answer
Jun 13, 2018

#x=5#

#y=6#

Explanation:

Linear equations can be solved by using method of substitution.

#x= 2y-7# ------> equation 1
#y - 3x = -9# ------> equation 2

Substitute equation 1 in equation 2 as shown below:

#y-3x=-9#

#y-3(2y-7) = -9#

#y-6y+21 = -9#

Simplify further to get value of #y# by making #y# the subject.

#-5y=-9-21#

#-5y=-30#

#y=(-30)/-5# = #30/5# =#6#

#y=6#

Substitute value of #y# in equation 1

#x= 2y-7# ------> equation 1

#x=2(6)-7#

#x=12-7#

#x=5#

Checking the answer:
#y - 3x = -9# ------> equation 2
#6-3(5) =-9#
#6-15=-9#----> Correct!