Question

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Answer 1

\(A= 2(x^6 + y^6) - 3(x^4 + y^4) +1\)

\(= 2x^4(x^2 - 1) + 2y^4(y^ - 1) - (x^4 + y^4) +1\)

\(=- 2x^4 .y^2 - 2y^4 .x^2 - [(x^2 +y^2)^2 - 2x^2.y^2] +1\)

\(=- 2x^2y^2.(x^2 + y^2) - 1 + 2x^2.y^2+1 \)

\(=- 2x^2y^2 - 1 + 2x^2y^2+1\)

\(=-1+1\)

\(=0\)

Vậy \(A=0\)

Answer 2

2(x²-y²)(x⁴+x²y²+y⁴)-3(x⁴+y⁴)+1

=2x⁴+2x²y²+2y⁴-3x⁴-3y⁴+1(thay x²- y²=1)

=-(x⁴-2x²y²+y⁴)+1

=-(x²-y²)²+1

=-1+1=0