Question 1151844
2x + 6y + 3z = −16
5x − 3y − 5z = 71
4x + 3y + 2z = 10
This is my first question! Find, x,y,z.
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I'll do this one.  You then try the others and email via the TY note for help or to check your work.
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I'll use elimination.
Multiply the 2nd & 3rd eqns by 2 so all the y coefficients are the same.
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<pre>
2x +  6y +  3z = −16
10x − 6y − 10z = 142
 8x + 6y +  4z = 20
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2x +  6y +  3z = −16
10x − 6y − 10z = 142
-------------------------------------- Add
12x - 7z = 126
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10x − 6y − 10z = 142
 8x + 6y +  4z = 20
------------------------------------- Add
18x - 6z = 162
Now there are 2 eqns in 2 variables, x & z
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12x - 7z = 126 --- Eqn A
18x - 6z = 162 --- Eqn B
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Multiply Eqn A by 1.5 to make the x coeff's the same:
18x - 10.5z = 189
18x - 6z = 162 --- Eqn B
------------------------------------------- Subtract
-4.5z = 27
-9z = 54
z = -6
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12x - 7z = 126 --- Eqn A
Sub for z and find x:
12x - 7*-6 = 126
12x = 84
x = 7
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</pre>
Sub for x & z in any equation and find y.