How do you solve 8x + 6y = 4 and 3x + 5y = 28?

1 Answer
Sep 8, 2015

Answer:

#(x,y) = (-74/11,106/11) = (6 8/11, 9 7/11)#

Explanation:

Given
[1]#color(white)("XXX")8x+6y=4#
[2]#color(white)("XXX")3x+5y=28#

Multiply [1] by 5 and [2] by 6 so we have two equations with the same coefficient for #y#
[3]#color(white)("XXX")40x+30=20#
[4]#color(white)("XXX")18x+30y=168#

Subtract [4] from [3]
[5]#color(white)("XXX")22x = -148#

Divide [5] by #22#
[6]#color(white)("XXX")x = -74/11#

Substituting #-74/11# for #x# in [2]
[7]#color(white)("XXX")3*(-74/11)+5y = 24#

Do some (tedious) arithmetic
[8]#color(white)("XXX")y= 106/11#