if x,y,z are distinct n real then the expression x^2+4y^2+9z^2-6yz-3zx-2xy is

non-negative
non-positive
zero
none of these.........

ab mera mazak mat udana.....coz i m new to quadratic..........n also i hav to study it myself coz i don't go to any coaching

Let a = x, b = 2y and c = 3z.

 

The given expression becomes

a²+b²+c²-ab-bc-ca = 0.5*(2a²+2b²+2c²-2ab-2bc-2ca)

 

= 0.5*[(a-b)²+(b-c)²+(c-a)²] >= 0. i.e. non-negative