How do solve the following linear system?: # 4x-3y=1 , 3x + y = -20 #?

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Answer 1 · 2016-01-27T05:53:16

#x=-59/13#
#y=-83/13#

Given -

#4x-3y=1# -----------------------------(1)
#3x+y=-20# ---------------------------(2)

Solve the 2nd equation for #y#

#y=-20-3x#

Substitute #y=-20-3x# in equation (1)

#4x-3(-20-3x)=1#
#4x+60+9x=1#
#13x=1-60#
#x=-59/13#

Substitute #x=-59/13# in equation (2)

#3(-59/13)+y=-20#
#-177/13+y=-20#
#y=-20+177/13=(-260+177)/13=-83/13#

#y=-83/13#