How do you solve the system of equations #4x - 5y = - 7# and #4x + 5y = - 17#?

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Answer 1 · 2017-06-21T14:18:40

#color(purple)(y=-1,x=-3#

#4x-5y=-7----(1)#

#4x+5y=-17----(2)#

#:.(1)-(2)#

#:.-10y=10#

#:.y=10/-10#

#:.color(purple)(y=-1#

Substitute y=-1 in (1)

#:.4x-5(color(purple)(-1))=-7#

#:.4x+5=-7#

#:.4x=-7-5#

#:.4x=-12#

#:.x=-12/4#

#:.color(purple)(x=-3#

Check:

Substitute #color(purple)(y=-1 , x=-3# in (1)

#:.4(color(purple)(-3))-5(color(purple)(-1))=-7#

#:.-12+5=-7#

#:.color(purple)(-7=-7#