How do you solve 3x -4y = 23 and 5x +2y = 21?

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Answer 1 · 2016-06-21T06:25:00

#x=5# and #y=-2#

The two equations are #3x-4y=23# ......(A) and

#5x+2y=21# ......(B)

As is apparent we can eliminate #y# by multiplying equation (B) by #2# and adding it to (A). We now get

#2xx(5x+2y)+3x-4y=2xx21+23# or

#10x+4y+3x-4y=42+23# or #13x=65# i.e. #x=65/13=5#

Now putting this value of #x# in (B), we get

#5xx5+2y=21# or #25+2y=21#

Hence #y=21-25=-4# or #y=-2#