How do you solve the system x + y = 12 and y = 2x?

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Answer 1 · 2018-07-27T09:54:05

#x=4, \ \ y=8#

Given equations:

#x+y=12\ .....(1)#

#y=2x#

#2x-y=0\ .........(2)#

Adding (1) & (2), we get

#x+y+2x-y=12+0#

#3x=12#

#x=12/3#

#x=4#

setting #x=4# in (1), we get

#4+y=12#

#y=8#

hence the solution is

#x=4, \ \ y=8#

Answer 2 · 2018-07-28T00:55:08

#(4,8)#

We already have #y# defined in terms of #x#, so we can plug this value into the first equation to get

#x+2x=12#

Combining like terms, this simplifies to

#3x=12#

Dividing both sides by #3#m we get

#x=4#

We can plug this value into the second equation to get

#y=2(4)=>y=8#

Therefore, the solution of these two equations is at the point

#(4,8)#

Hope this helps!