on behalf of @jrzyby1

solve the system
x+4y-z=3 (1)
x+5y-2z=5 (2)
3x+12y-3z=9 (3)

Question

on behalf of @jrzyby1 

solve the system
     x+4y-z=3      (1)
     x+5y-2z=5   (2)
 3x+12y-3z=9   (3)

lgbasallote · Answer

x + 4y - z = 3
x + 5y - 2z = 5

subtract the equations

9y + z = -2 <-- (4)

unklerhaukus · Answer

times the first equation by three,
then find the difference with the third equation

unklerhaukus · Answer

(1),(3) are the same

unklerhaukus · Answer

infinite solutions

anonymous · Answer

Since 1 and 3 are the same, aren't there an infinite number of solutions?

lgbasallote · Answer

hmm yep equation 1 and 3 wont intersect

anonymous · Answer

gotcha.

unklerhaukus · Answer

there is an infinite  line of solutions

anonymous · Answer

I wass't sure and I tried to put the second equation into the first to see if it could be worked, hence the origin of all this. lol

anonymous · Answer

cool. thank you much

turingtest · Answer

@jrzyby1 fyi to ask a new question you will have to close your old post (which I think you left open)