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HELP! how to solve system of equations
x2y+z=1
y+2z=4
x+y+3z=5
what do we do when there is a missing variable??? :(
 8 months ago
 8 months ago
HELP! how to solve system of equations x2y+z=1 y+2z=4 x+y+3z=5 what do we do when there is a missing variable??? :(
 8 months ago
 8 months ago

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woody84Best ResponseYou've already chosen the best response.0
what are you solving for??
 8 months ago

mathcalculusBest ResponseYou've already chosen the best response.0
I'm not sure what to do since the x is missing.
 8 months ago

DirectrixBest ResponseYou've already chosen the best response.1
Write the system as: x  2y +z =1 0x +y+ 2z=4 x + y + 3z = 5 In the first and third equations, eliminate the variable x. Then, you will have a system of 2 by 2 equations in the unknowns y and z. Of those two equations, eliminate a variable and solve for the other. If you are allowed to use technology, take a look at the online 3 x 3 linear equation system solver at: http://math.bd.psu.edu/~jpp4/finitemath/3x3solver.html @mathcalculus
 8 months ago

mathcalculusBest ResponseYou've already chosen the best response.0
im trying to solve it step by step
 8 months ago

DirectrixBest ResponseYou've already chosen the best response.1
x  2y +z =1 0x +y+ 2z=4 x + y + 3z = 5 x  2y +z =1 x  2y +z =1 x + y + 3z = 5 multiply through by 1 > x  y  3z = 5  3y  2z = 4
 8 months ago

mathcalculusBest ResponseYou've already chosen the best response.0
i got a little lost. now i know why
 8 months ago

mathcalculusBest ResponseYou've already chosen the best response.0
i got that, so what about the second equation?
 8 months ago

DirectrixBest ResponseYou've already chosen the best response.1
@mathcalculus Your Task: Solve this system  Just add them. 3y  2z = 4 y+ 2z=4 
 8 months ago

mathcalculusBest ResponseYou've already chosen the best response.0
it bothers me that the 0x is there.
 8 months ago

DirectrixBest ResponseYou've already chosen the best response.1
Don't look at it. When I eliminated the "x" in equations #1 and #3, the 0x was not an issue.
 8 months ago

mathcalculusBest ResponseYou've already chosen the best response.0
i got this: 2y=0
 8 months ago

mathcalculusBest ResponseYou've already chosen the best response.0
but it can't be. it's undefined.
 8 months ago

DirectrixBest ResponseYou've already chosen the best response.1
Note that here: Solve this system  Just add them. 3y  2z = 4 y+ 2z=4  I excluded the 0x term. It is just a placeholder of sorts.
 8 months ago

DirectrixBest ResponseYou've already chosen the best response.1
2y = 0 y= 0/2 y = 0> You have division by 0 and division into 0 mixed up.
 8 months ago

mathcalculusBest ResponseYou've already chosen the best response.0
okay i got that step right.
 8 months ago

DirectrixBest ResponseYou've already chosen the best response.1
It is wrong. But, unless you show your steps, I cannot help you find the error.
 8 months ago

mathcalculusBest ResponseYou've already chosen the best response.0
i got it right! x=1 y=0 z=2 ! =]
 8 months ago

mathcalculusBest ResponseYou've already chosen the best response.0
thanks so much! i really aprreciate it!
 8 months ago
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