@_@ Need help...

[asterio]

Ahhhh... This question drives me mad...





The simulaneous equations:
(n-3)x + 3y = 6
2x + (n+3)y= n
have a unique solution for n.


can someone plz tell me HOW do you find it...?

[/0]

Is it asking for which values of n the equations have a unique solution?

In a matrix,



There will be a unique solution provided the determinant of the coefficient matrix is non-zero. That gives you your values of n.

[asterio]

nah... its a multi choice question


A: n (include) R\{0}
B: n (include) R\{-3,3}
C: n (include) R\{-15^0.5,15^0.5}
D: n (include) R\[-3,3]
E: n = 3 or n = -3

[/0]

Well, the determinant is



When that equals zero,

So the values of 'n' for which you will get a unique solution are

[tcg93]

I know /0 is right, but when a question asks for unique solution, doesn't it mean that one set of solutions should exist?
When det = 0, there should be no solutions instead... (either because they lines don't intersect or the lines are equal)

Yes, so the answer is R\{-15^0.5,15^0.5} as it is all values when det does not equal 0