How do you get x= y= without the z?

Question

1x + 2y = 7
-1x + 0y = -5
6x + 6y = 9

there is no Z just X=, Y=

Answer 1

You haven't listed a 'z' - the answers are trivial without this

Answer 2

OK!

Two equations in two unknowns should be solvable.

Look at equation #2:
-1x + 0y =-5
-1x = -5
x=5

Substitute into equation #1:
1(5) +2 (y) =7
5 + 2y = 7
2y = 2
y =1

You now have x and y.

However, if you substitute each into equation #3, you get:
6(5) + 6(1) = 36, which does *not* = 9.

Thus, one of these equations does not belong. (In order for 3 equations in two variables to be solvavble, two of the equations must be equivalent, or the third must be an explicit combination of the other two.) Review your text or ask your teacher!

Answer 3

from the second line you know : x = 5
inserting in the first line you have 1+2y=7 ==> y=1
now look on the third line : 30 + 6 = 36 And not 9 ==> this systems has no solutions !

May be you need an approximation to reduce the error (the minimum mean square method is often used for this kind of problems)

Answer 4

These three equations cannot have the same (x,y) solution. For example, the middle equation has the solution x = 5 (for all y's), which only works for a few y's in the other two equations.

Please re-check the problem.

Answer 5

-x= -5
x = 5
now insert 5 everywhere x is
5 + 2y = 7
-5
2y=2
y=1
never mind doug is right listen to him

Answer 6

By noticing that those 3 equations can't *possibly* form a simultaneous system. Which you'd be able to do if you actually *studied* your book instead of asking other people to do your homework for you ☺


Doug