1

### IIT-JEE 1979

If x, y and z are real and different and $$\,u = {x^2} + 4{y^2} + 9{z^2} - 6yz - 3zx - 2xy$$, then u is always.
A
non negative
B
zero
C
non positive
D
none of these
2

### IIT-JEE 1979

The equation x + 2y + 2z = 1 and 2x + 4y + 4z = 9 have
A
only one solution
B
only two solution
C
Infinite number of solutions
D
None of these.

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