How do you solve the system of equations #x+ 2y = 3# and #- 2x + y = 1#?

1 Answer
Tsepi · Stefan V.
Jul 30, 2017

Pick either one of the equations and make either #x# or #y# the subjects of the formula and substitute the value of either #y# or #x# into the other equation.

Explanation:

I.e. #" "x=3-2y" "# (from first equation)

Now substitute #x# above into second equation:

# -2(3-2y)+y=1#

#-6+4y+y=1#

#-6+5y=1#

#5y=7#

Therefore

#y=7/5#

Now substitute the #y#-value into the equation to find #x#:

#-2x+7/5=1#

#-2x=5/5(=1) -7/5#

#x=1/5#

Thus, #x# and #y# for the 2nd equation #=1/5# and #=7/5#.

You must again substitute either into the 1st equation to find those values. Just remember to check the answers!

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