Originally Posted by

**Adrian** I attempted this problem but the answers I got seem sort of unlikely so if somebody could check what I did and tell me where I went wrong (if I did) then that would be amazing.

Solve for x, y, and z.

xy-2sqrt(y) + 3zy = 8

2xy - 3sqrt(y) + 2zy = 7

-xy + sqrt(y) + 2zy = 4

And my solution:

[1 -2 3 | 8] [1 -2 3 | 8] [1 -2 3 | 8]

[2 -3 2 | 7] [0 1 -4 | -9] [0 1 -4 | -9]

[-1 1 2 | 4] [0 -1 5 | 12] [0 0 1 | 12]

This gives that zy = 12

Then I continued row-echelon on the matrix:

[1 -2 3 | 8]

[0 1 0 | 39]

[0 0 1 | 12]

This gives that sqrt(y) = 39, thus squaring both sides, y = 1521

Then since zy = 12, and y = 1521, yz = 12/1521 = 0.00789

Then further reducing the matrix:

[1 -2 0 | -28] [1 0 0 | 56]

[0 1 0 | 39] [0 1 0 | 39]

[0 0 1 | 12] [0 0 1 | 12]

This means that xy = 56 and since y = 1521, x = 56/1521 = 0.0368

I don't think this can be right given the decimal numbers for x and z, so if somebody could see where I went wrong that would be great, and sorry for the not-so-neat matrices.

Thanks