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

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Answer 1 · 2017-06-21T14:18:40

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

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

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

$:.(1)-(2)$

$:.-10y=10$

$:.y=10/-10$

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

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)

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

$:.-12+5=-7$

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

How do you solve the system of equations 4x - 5y = - 74x−5y=−74x - 5y = - 7 and 4x + 5y = - 174x+5y=−174x + 5y = - 17?