How do you solve the system of equations: -3x+y=-4 and 2x-y=1?

1 Answer
Aug 12, 2015

Answer:

Add the given equations together to get an equation in terms or just #x#; solve for #x#; then use the solution value in one of the given equations to determine #y#
#(x,y) = (-5, -11)#

Explanation:

[1]#color(white)("XXXX")##-3x+y = 4#
[2]#color(white)("XXXX")##2x-y = 1#

Adding [1] and [2]
[3]#color(white)("XXXX")##-x = 5#
Multiplying by #(-1)#
[4]#color(white)("XXXX")##x = -5#

Substituting #(-5)# for #x# in [1]
[5]#color(white)("XXXX")##-3(-5) + y = 4#

Simplifying
[6]#color(white)("XXXX")##y = -11#