Question

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Answer 1

Step-by-step explanation:

29.

(a+b+c)^2=a^2+b^2+c^2+2ab+2bc+2ac

By using the above identity we can write that

9x^2+y^2+z^2+6xy+2yz+6zx=(3x+y+z)^2

and putting the value of x=1 y=2 z=-1

(3×1+2-1)=4