How do you solve # 5x – 6y = 21# and #x - 2y = 5# using substitution?

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Answer 1 · 2016-03-05T08:00:23

Solution is #x=3# and #y=-1#

To solve #5x–6y=21# and #x−2y=5# using substitution, we first get value of #x# from second equation and put it in first equation.

From second equation #x−2y=5#, we get #x=5+2y# ... (A)

Hence second equation becomes

#5(5+2y)–6y=21# i.e. #25+10y-6y=21# or

#4y=21-25=-4# and hence #y=-4/4=-1#.

Now putting this in (A), we get #x=5+2xx(-1)# or

#x=5-2=3#

Hence solution is #x=3# and #y=-1#