How do you solve the system of equations algebraically x-y-z=7, x+2y+3z=-12, 3x-2y+7z=30xyz=7,x+2y+3z=12,3x2y+7z=30?

1 Answer
Mar 29, 2017

Multiply the first equation by -3 first. Then go ahead, x=2/26; y=-226/26 and z=46/26

Explanation:

When you multiply the first equation by -3, you will get:
-3x+3y+3z=-213x+3y+3z=21
Then combine this equation with the second. Yielding,
y=9-10zy=910z.

When you see y (in the first (original equation)), write this and for the second original equation do the same.

You will get x+9z=16x+9z=16 and x-17z=-30x17z=30. You can multiply either the first equation by -1 or the second by -1. You will get
z=46/26z=4626

Since y=9-10zy=910z, you can find y now. y=9-(460/26)y=9(46026) or y=-226/26y=22626.

Finally, you can easily solve using any original equation. x=2/26x=226.