solve x + y + z = 4, x - 2y - z = 1, 2x - y - 2z = -1
- Thread starter jferrel8
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- Apr 12, 2005
- Messages
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Time for lecture #218-3b.
If you REALLY have no clue, you totally have not been paying attention in class. You should do better than that.
Surely you have solved a system of equations before.
How about this one?
2x=8
That's one equation in one variable. Can you solve it?
How about this one?
x-2y=1
2x-y = -1
That's two equations in two variables. Can you solve it?
Show me those and I will believe you are ready for the 3x3. Or, you could use what you learn and apply it to the original problem statement and you could show us the answer and your work!
If you REALLY have no clue, you totally have not been paying attention in class. You should do better than that.
Surely you have solved a system of equations before.
How about this one?
2x=8
That's one equation in one variable. Can you solve it?
How about this one?
x-2y=1
2x-y = -1
That's two equations in two variables. Can you solve it?
Show me those and I will believe you are ready for the 3x3. Or, you could use what you learn and apply it to the original problem statement and you could show us the answer and your work!
- Joined
- Feb 4, 2004
- Messages
- 16,582
I'm sorry to hear that you missed the weeks that your class spent studying systems of equations, that your book is confusing, and that the class notes you got from a friend didn't help much. :shock:jferrel8 said:
Obviously, we cannot here replace those hours of classroom instruction, so we cannot provide the lessons you need. Fortunately, there are loads of great lessons available online! :wink:
. . . . .Google results for "solving systems linear equations"
Give yourself at least a couple of days to study and absorb the material. Review at least two lessons from the above link, taking the time to work through the examples yourself. Then attempt the posted exercise, using whichever method you prefer. Then, if you get stuck, you'll be able to reply, showing your work and reasoning so far, and will be in a position to comprehend the hints and helps you here received.
Have fun!
Eliz.
solve for,
1x+1y+1z=4
1x-2y-1z=1
2x-1y-2z= -1
first, 2(1x+1y+1z=4)
and i got....
2x+2y+2z=8
1x-2y-1z=1
....i got 3x+1z=9
second, -2(2x-1y-2z= -1)
and i got...
1x-2y-1z=1
-4x+2y+4z=2
...i got -3x+3z=3....so.....
3x+1z=9
-3x+3z=3...i got z=3
third, i plugged z=3 into...
-3x+3(3)=3 and i got x=2
so....
2(2)-1y-2(3)= -1 and i got y=-1
therefore, the solution equals (2,-1,3)
1x+1y+1z=4
1x-2y-1z=1
2x-1y-2z= -1
first, 2(1x+1y+1z=4)
and i got....
2x+2y+2z=8
1x-2y-1z=1
....i got 3x+1z=9
second, -2(2x-1y-2z= -1)
and i got...
1x-2y-1z=1
-4x+2y+4z=2
...i got -3x+3z=3....so.....
3x+1z=9
-3x+3z=3...i got z=3
third, i plugged z=3 into...
-3x+3(3)=3 and i got x=2
so....
2(2)-1y-2(3)= -1 and i got y=-1
therefore, the solution equals (2,-1,3)