How do you solve the following system: #3x + 4y = 11 , x-3y=20 #?

1 Answer
Feb 3, 2016

Answer:

The solution for the system of equations is:
#color(blue)(y = -49/13#

#color(blue)(x =113/13#

Explanation:

#color(blue)(3x) +4y =11# .......equation #(1)#

#x -3y =20#,multiplying by #3#
#color(blue)(3x) -9y =60# .......equation #(2)#

Solving by elimination

Subtracting equation #2# from #1#

#cancelcolor(blue)(3x) +4y =11#
#-cancelcolor(blue)(3x) +9y =-60#

#13y = -49#

#color(blue)(y = -49/13#

Finding #x# from equation #2#:

#x -3y =20#

#x =20+3y#

#x =20+3 xx (-49/13)#

#x =20-147/13#

#x =260/13-147/13#

#color(blue)(x =113/13#