How do you solve 2x - 5y = 11 and 4x + 10y = 18?

1 Answer
Alan P.
Sep 17, 2015

(x,y) = (5, -1/5)

Explanation:

[1]color(white)("XXX")2x-5y=11
[2]color(white)("XXX")4x+10y=18

Multiply [1] by 2
[3]color(white)("XXX")4x-10y=22

Subtract [3] from [2]
[4]color(white)("XXX")20y = -4

Divide [4] by 20
[5]color(white)("XXX")y = -1/5

Substitute (-1/5) for y in [1]
[6]color(white)("XXX")2x-5(-1/5)=11

Simplify
[7]color(white)("XXX")2x+1=11

Subtract 1
[8]color(white)("XXX")2x=10

Divide by 2
[9]color(white)("XXX")x=5

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