How do you solve the following system?: #3x+3y=-21 , 6x+5y=18 #

Question

2412 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2018-07-22T09:29:52

#x=53, \ \ y=-60#

Given equations

#3x+3y=-21\ ........(1)#

#6x+5y=18\ ........(2)#

Multiplying (1) by #2# & subtracting from (2) as follows

#6x+5y-2(3x+3y)=18-2(-21)#

#6x+5y-6x-6y=18+42#

#-y=60#

#y=-60#

Setting the value of #y# in (1), we get

#3x+3(-60)=-21#

#3x-180=-21#

#3x=180-21#

#x=\frac{159}{3}#

#x=53#

Answer 2 · 2018-07-22T16:14:13

#x=53# and #y=-60#

#2*(3x+3y)-(6x+5y)=2*(-21)-18#

#(6x+6y)-(6x+5y)=(-42)-18#

#y=-60#

So,

#3x+3*(-60)=-21#

#3x-180=-21#

#3x=159# or #x=53#