BITSAT2020MathematicsBasics of MathematicsActual
If x, y and z are real numbers, the x²+4 y²+9 z²-6 y z-3 z x-2 x y is always
Options
- Apositive
- Bnon-positive
- Czero
- Dnon-negative
Correct answer
D. non-negative
Step-by-step solution
x²+4 y²+9 z²-6 y z-3 z x-2 x y=x²+(2 y)²+(3 z)²-(2 y)(3 z)-(3 z)(x)-x(2 y) 0 x, y, z [ a ²+ b ²+ c ²- ab - bc - ca 0 ]