Question

Factorise 9x^2+y^2+z^2-6xy+2yz-6zx. Hence find its value if x=1,y=2,z=-1

Answer 1

Explanation:

9(1)²+ (2)²+(-1)²-6×1×2+2×2×-1 -6×-1×1

= 9+4+1-12-4+6

=4

Answer 2

Answer:

$(9) {}^{2} +(2) {}^{2}+(-1) {}^{2} - 6 \times 1\times2+2\times2\times( - 1)+ 6\times( - 1)\times 1$

Explanation:

81+4+1-12+(-4)+6

81+4+1-12-4+6

92-16

76