Question 1203438
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There are an endless number of different ways to solve this system of equations; the other tutor has shown one.<br>
Like the other tutor, I changed the three equations into equivalent forms to get "9x" as a term in all three equations.  Then from there I went a different direction the they did.<br>
{{{9x+18y-3z=18}}} [1]
{{{9x-9y+15z=-18}}} [2]
{{{9x+9y-2z=11}}} [3]<br>
Do [1]-[2] to eliminate x to get one equation in y and z; do [1]-[3] to get another.<br>
{{{27y-18z=36}}} --> {{{9y-6z=12}}} [4]
{{{9y-z=7}}} [5]<br>
Do [4]-[5] to eliminate y and solve for z<br>
{{{-5z=5}}}
{{{z=-1}}}<br>
Substitute z=-1 in [5] and solve for y<br>
{{{9y+1=7}}}
{{{9y=6}}}
{{{y=6/9=2/3}}}<br>
Substitute z=-1 and y=2/3 in [1] to solve for x<br>
{{{9x+12+3=18}}}
{{{9x+15=18}}}
{{{9x=3}}}
{{{x=3/9=1/3}}}<br>
ANSWER: (x,y,z) = (1/3,2/3,-1)<br>