Question 665382

how to solve:
x+2z=5
-4x+6y=0
x-2z=9


{{{system (x + 2z = 5_______eq (i),
- 4x + 6y = 0_____eq (ii),
x - 2z = 9_______eq (iii))}}}

4z = - 4 ------ Subtracting eq (iii) from eq (i)
z = {{{(- 4)/4}}}, or {{{highlight_green(z = - 1)}}}


x + 2(- 1) = 5 ------ Substituting – 1 for z in eq (i)
x – 2 = 5
x = 5 + 2, or {{{highlight_green(x = 7)}}}
 

- 4(7) + 6y = 0 ------ Substituting 7 for x in eq (ii) 
- 28 + 6y = 0
6y = 28
y = {{{28/6}}}, or {{{highlight_green(y = 4&2/3)}}}


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