How do you find the ordered pair that is the solution of equations 5x - 4y + 3 = 15 and 9y = 4x + 31?

1 Answer
Alan P.
Jul 27, 2016

(x,y)=color(green)(""(8,7))

Explanation:

Rearrange the given equations into standard form:
[1]color(white)("XXX")5x-4y=12
[2]color(white)("XXX")4x-9y=-31

[1]xx4 minus [2]xx5
color(white)("XXXX")(20x-16y=color(white)("XXx")48)
color(white)("XXX")underline(-(20x-45y=-155))
color(white)("XXXXXXXXX")29y=color(white)("XX")203

color(white)("XXX")rarr y=203/29=7

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Similarly, [1]xx9 minus [2]xx4

color(white)("XXX")rarr x=8

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