Question

-2x-5y+z=15
4x-y+3z=15
3x-2y+2z=13
Use the substitution method to solve the system what would be the equations left if z was isolated first? Please help I'm so lost

Answer 1

Solve the first equation in terms of z and then put that value of z into the second 2 equations. Simplify, and now you have 2 equations in 2 unknowns.

Answer 2

I got 10x-16y=-30
7x-12y=-15
I don't think its right though

Answer 3

-2x-5y+z=15 eq1) mult by 3-> -6x-15y+3z=45
4x-y+3z=15 eq2) - (4x - y +3z=15)
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-10x -14y = 30 eq 4)

-2x-5y+z=15 eq1) mult by 2 -> -4x -10y+2z=30
3x-2y+2z=13 eq3) -> -(3x -2y +2z=13)
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-7x -8y = 17 eq 5)

eq 4) mult by 7 --> -70x -98y = 210
eq 5) mult by 10 -> -(-70x -80y=170)
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-18y=40
y=-40/18
y=-20/9 ....ans

sub y into eq 4) --> -10x -14(-20/9) =30
x=1/9 .....ans

sub x and y into eq1) --> -2(1/9) -5(-20/9) +z=15 gives
z=4.111 .......ans

Answer 4

good luck and have fun ...lol